21259969 has 4 divisors (see below), whose sum is σ = 21295044. Its totient is φ = 21224896.

The previous prime is 21259967. The next prime is 21260003. The reversal of 21259969 is 96995212.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 5760000 + 15499969 = 2400^2 + 3937^2 .

It is a cyclic number.

It is not a de Polignac number, because 21259969 - 2¹ = 21259967 is a prime.

It is a super-2 number, since 2×21259969² = 903972563761922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21259961) 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, 16612 + ... + 17845.

It is an arithmetic number, because the mean of its divisors is an integer number (5323761).

Almost surely, 2^21259969 is an apocalyptic number.

It is an amenable number.

21259969 is a deficient number, since it is larger than the sum of its proper divisors (35075).

21259969 is an equidigital number, since it uses as much as digits as its factorization.

21259969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35074.

The product of its digits is 87480, while the sum is 43.

The square root of 21259969 is about 4610.8533917270. The cubic root of 21259969 is about 277.0262196766.

The spelling of 21259969 in words is "twenty-one million, two hundred fifty-nine thousand, nine hundred sixty-nine".