21202438656 has 160 divisors (see below), whose sum is σ = 67952079360. Its totient is φ = 5738950656.

The previous prime is 21202438633. The next prime is 21202438661. The reversal of 21202438656 is 65683420212.

It is a super-2 number, since 2×21202438656² (a number of 21 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 152395 + ... + 256181.

It is an arithmetic number, because the mean of its divisors is an integer number (424700496).

Almost surely, 2^21202438656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21202438656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33976039680).

21202438656 is an abundant number, since it is smaller than the sum of its proper divisors (46749640704).

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

21202438656 is a wasteful number, since it uses less digits than its factorization.

21202438656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103834 (or 103818 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 39.

Adding to 21202438656 its reverse (65683420212), we get a palindrome (86885858868).

The spelling of 21202438656 in words is "twenty-one billion, two hundred two million, four hundred thirty-eight thousand, six hundred fifty-six".