21269531 has 4 divisors (see below), whose sum is σ = 22389000. Its totient is φ = 20150064.

The previous prime is 21269527. The next prime is 21269537. The reversal of 21269531 is 13596212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21269531 - 2² = 21269527 is a prime.

It is a super-2 number, since 2×21269531² = 904785897919922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21269494 and 21269503.

It is not an unprimeable number, because it can be changed into a prime (21269537) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559706 + ... + 559743.

It is an arithmetic number, because the mean of its divisors is an integer number (5597250).

Almost surely, 2^21269531 is an apocalyptic number.

21269531 is the 2063-rd centered decagonal number.

21269531 is a deficient number, since it is larger than the sum of its proper divisors (1119469).

21269531 is a wasteful number, since it uses less digits than its factorization.

21269531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1119468.

The product of its digits is 3240, while the sum is 29.

The square root of 21269531 is about 4611.8901764895. The cubic root of 21269531 is about 277.0677457277.

The spelling of 21269531 in words is "twenty-one million, two hundred sixty-nine thousand, five hundred thirty-one".