151687821777921 has 243 divisors, whose sum is σ = 275414945853411. Its totient is φ = 80340781435200.

The previous prime is 151687821777901. The next prime is 151687821777983. The reversal of 151687821777921 is 129777128786151.

It is a happy number.

The square root of 151687821777921 is 12316161.

It is a perfect power (a square), and thus also a powerful number.

151687821777921 is a `hidden beast` number, since 1 + 516 + 8 + 7 + 8 + 2 + 17 + 7 + 7 + 92 + 1 = 666.

151687821777921 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 22439026890225 + 129248794887696 = 4736985^2 + 11368764^2 .

It is not a de Polignac number, because 151687821777921 - 2¹⁵ = 151687821745153 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 151687821777921.

It is not an unprimeable number, because it can be changed into a prime (151687821777901) by changing a digit.

It is a polite number, since it can be written in 242 ways as a sum of consecutive naturals, for example, 100389027556 + ... + 100389029066.

Almost surely, 2^{151687821777921} is an apocalyptic number.

151687821777921 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

151687821777921 is the 12316161-st square number.

151687821777921 is the 6158081-st centered octagonal number.

It is an amenable number.

151687821777921 is a deficient number, since it is larger than the sum of its proper divisors (123727124075490).

151687821777921 is a wasteful number, since it uses less digits than its factorization.

151687821777921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3114 (or 1557 counting only the distinct ones).

The product of its digits is 165957120, while the sum is 72.

The spelling of 151687821777921 in words is "one hundred fifty-one trillion, six hundred eighty-seven billion, eight hundred twenty-one million, seven hundred seventy-seven thousand, nine hundred twenty-one".