1621815809238 has 80 divisors (see below), whose sum is σ = 3868317486000. Its totient is φ = 506397754368.

The previous prime is 1621815809197. The next prime is 1621815809249. The reversal of 1621815809238 is 8329085181261.

1621815809238 is a `hidden beast` number, since 1 + 6 + 21 + 8 + 1 + 580 + 9 + 2 + 38 = 666.

It is a super-2 number, since 2×1621815809238² (a number of 25 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2686203 + ... + 3234086.

It is an arithmetic number, because the mean of its divisors is an integer number (48353968575).

Almost surely, 2^{1621815809238} is an apocalyptic number.

1621815809238 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

1621815809238 is an abundant number, since it is smaller than the sum of its proper divisors (2246501676762).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1621815809238 is a wasteful number, since it uses less digits than its factorization.

1621815809238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5920411 (or 5920402 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 1621815809238 in words is "one trillion, six hundred twenty-one billion, eight hundred fifteen million, eight hundred nine thousand, two hundred thirty-eight".