21631643929 has 9 divisors (see below), whose sum is σ = 25164538581. Its totient is φ = 18540526620.

The previous prime is 21631643927. The next prime is 21631643933. The reversal of 21631643929 is 92934613612.

The square root of 21631643929 is 147077.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 21631643929 - 2¹ = 21631643927 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21631643927) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 1019034 + ... + 1040044.

Almost surely, 2^21631643929 is an apocalyptic number.

21631643929 is the 147077-th square number.

21631643929 is the 73539-th centered octagonal number.

It is an amenable number.

21631643929 is a deficient number, since it is larger than the sum of its proper divisors (3532894652).

21631643929 is an frugal number, since it uses more digits than its factorization.

21631643929 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42036 (or 21018 counting only the distinct ones).

The product of its digits is 419904, while the sum is 46.

The spelling of 21631643929 in words is "twenty-one billion, six hundred thirty-one million, six hundred forty-three thousand, nine hundred twenty-nine".