21423120138 has 64 divisors (see below), whose sum is σ = 56773509120. Its totient is φ = 5854763376.

The previous prime is 21423120137. The next prime is 21423120181. The reversal of 21423120138 is 83102132412.

21423120138 is a `hidden beast` number, since 2 + 1 + 423 + 1 + 201 + 38 = 666.

It is a super-2 number, since 2×21423120138² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21423120137) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1223370 + ... + 1240757.

It is an arithmetic number, because the mean of its divisors is an integer number (887086080).

Almost surely, 2^21423120138 is an apocalyptic number.

21423120138 is an abundant number, since it is smaller than the sum of its proper divisors (35350388982).

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

21423120138 is a wasteful number, since it uses less digits than its factorization.

21423120138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2464168 (or 2464162 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 27.

The spelling of 21423120138 in words is "twenty-one billion, four hundred twenty-three million, one hundred twenty thousand, one hundred thirty-eight".