21156773238 has 32 divisors (see below), whose sum is σ = 49059187200. Its totient is φ = 6745637448.

The previous prime is 21156773237. The next prime is 21156773257. The reversal of 21156773238 is 83237765112.

21156773238 is a `hidden beast` number, since 2 + 11 + 567 + 73 + 2 + 3 + 8 = 666.

It is a junction number, because it is equal to n+sod(n) for n = 21156773193 and 21156773202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21156773237) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 8515978 + ... + 8518461.

It is an arithmetic number, because the mean of its divisors is an integer number (1533099600).

Almost surely, 2^21156773238 is an apocalyptic number.

21156773238 is an abundant number, since it is smaller than the sum of its proper divisors (27902413962).

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

21156773238 is a wasteful number, since it uses less digits than its factorization.

21156773238 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17034473 (or 17034467 counting only the distinct ones).

The product of its digits is 423360, while the sum is 45.

The spelling of 21156773238 in words is "twenty-one billion, one hundred fifty-six million, seven hundred seventy-three thousand, two hundred thirty-eight".