21023402138 has 8 divisors (see below), whose sum is σ = 33390109332. Its totient is φ = 9893365696.

The previous prime is 21023402137. The next prime is 21023402171. The reversal of 21023402138 is 83120432012.

It can be written as a sum of positive squares in 2 ways, for example, as 20732256169 + 291145969 = 143987^2 + 17063^2 .

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

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21023402137) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 309167645 + ... + 309167712.

Almost surely, 2^21023402138 is an apocalyptic number.

21023402138 is a deficient number, since it is larger than the sum of its proper divisors (12366707194).

21023402138 is a wasteful number, since it uses less digits than its factorization.

21023402138 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 618335376.

The product of its (nonzero) digits is 2304, while the sum is 26.

The spelling of 21023402138 in words is "twenty-one billion, twenty-three million, four hundred two thousand, one hundred thirty-eight".