77716021 has 8 divisors (see below), whose sum is σ = 79960664. Its totient is φ = 75479040.

The previous prime is 77716003. The next prime is 77716087. The reversal of 77716021 is 12061777.

It can be written as a sum of positive squares in 4 ways, for example, as 1782225 + 75933796 = 1335^2 + 8714^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77716021 - 2²³ = 69327413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77716091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23341 + ... + 26461.

It is an arithmetic number, because the mean of its divisors is an integer number (9995083).

Almost surely, 2^77716021 is an apocalyptic number.

It is an amenable number.

77716021 is a deficient number, since it is larger than the sum of its proper divisors (2244643).

77716021 is a wasteful number, since it uses less digits than its factorization.

77716021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3831.

The product of its (nonzero) digits is 4116, while the sum is 31.

The square root of 77716021 is about 8815.6690613929. The cubic root of 77716021 is about 426.7467139717.

Adding to 77716021 its reverse (12061777), we get a palindrome (89777798).

The spelling of 77716021 in words is "seventy-seven million, seven hundred sixteen thousand, twenty-one".