21053487637 has 18 divisors (see below), whose sum is σ = 26379287298. Its totient is φ = 16654807008.

The previous prime is 21053487619. The next prime is 21053487641. The reversal of 21053487637 is 73678435012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 4105093041 + 16948394596 = 64071^2 + 130186^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21053487637 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21053487617) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3659239 + ... + 3664987.

It is an arithmetic number, because the mean of its divisors is an integer number (1465515961).

Almost surely, 2^21053487637 is an apocalyptic number.

It is an amenable number.

21053487637 is a deficient number, since it is larger than the sum of its proper divisors (5325799661).

21053487637 is an frugal number, since it uses more digits than its factorization.

21053487637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11525 (or 5769 counting only the distinct ones).

The product of its (nonzero) digits is 846720, while the sum is 46.

The spelling of 21053487637 in words is "twenty-one billion, fifty-three million, four hundred eighty-seven thousand, six hundred thirty-seven".