21398123904 has 64 divisors (see below), whose sum is σ = 58048151040. Its totient is φ = 6980942336.

The previous prime is 21398123897. The next prime is 21398123909. The reversal of 21398123904 is 40932189312.

It is a tau number, because it is divible by the number of its divisors (64).

It is a super-2 number, since 2×21398123904² (a number of 21 digits) contains 22 as substring.

It is a hoax number, since the sum of its digits (42) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21398123909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 574764 + ... + 610859.

It is an arithmetic number, because the mean of its divisors is an integer number (907002360).

Almost surely, 2^21398123904 is an apocalyptic number.

21398123904 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

21398123904 is an abundant number, since it is smaller than the sum of its proper divisors (36650027136).

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

21398123904 is a wasteful number, since it uses less digits than its factorization.

21398123904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1185687 (or 1185675 counting only the distinct ones).

The product of its (nonzero) digits is 93312, while the sum is 42.

The spelling of 21398123904 in words is "twenty-one billion, three hundred ninety-eight million, one hundred twenty-three thousand, nine hundred four".