21265513929 has 63 divisors (see below), whose sum is σ = 35117225437. Its totient is φ = 12861941400.

The previous prime is 21265513891. The next prime is 21265513931. The reversal of 21265513929 is 92931556212.

The square root of 21265513929 is 145827.

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

21265513929 is a `hidden beast` number, since 2 + 1 + 2 + 6 + 551 + 3 + 92 + 9 = 666.

It is not a de Polignac number, because 21265513929 - 2¹⁵ = 21265481161 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21265513729) by changing a digit.

It is a polite number, since it can be written in 62 ways as a sum of consecutive naturals, for example, 43310374 + ... + 43310864.

Almost surely, 2^21265513929 is an apocalyptic number.

21265513929 is the 145827-th square number.

21265513929 is the 72914-th centered octagonal number.

It is an amenable number.

21265513929 is a deficient number, since it is larger than the sum of its proper divisors (13851711508).

21265513929 is an frugal number, since it uses more digits than its factorization.

21265513929 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1022 (or 505 counting only the distinct ones).

The product of its digits is 291600, while the sum is 45.

The spelling of 21265513929 in words is "twenty-one billion, two hundred sixty-five million, five hundred thirteen thousand, nine hundred twenty-nine".