21279769 has 9 divisors (see below), whose sum is σ = 24791637. Its totient is φ = 18212124.

The previous prime is 21279757. The next prime is 21279781. The reversal of 21279769 is 96797212.

The square root of 21279769 is 4613.

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

It is an interprime number because it is at equal distance from previous prime (21279757) and next prime (21279781).

It is not a de Polignac number, because 21279769 - 2⁵ = 21279737 is a prime.

It is a super-2 number, since 2×21279769² = 905657137386722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21279749) 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, 31962 + ... + 32620.

Almost surely, 2^21279769 is an apocalyptic number.

21279769 is the 4613-rd square number.

21279769 is the 2307-th centered octagonal number.

It is an amenable number.

21279769 is a deficient number, since it is larger than the sum of its proper divisors (3511868).

21279769 is an frugal number, since it uses more digits than its factorization.

21279769 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1332 (or 666 counting only the distinct ones).

The product of its digits is 95256, while the sum is 43.

The cubic root of 21279769 is about 277.1121937313.

The spelling of 21279769 in words is "twenty-one million, two hundred seventy-nine thousand, seven hundred sixty-nine".