21915969 has 4 divisors (see below), whose sum is σ = 29221296. Its totient is φ = 14610644.

The previous prime is 21915961. The next prime is 21915979. The reversal of 21915969 is 96951912.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21915969 - 2³ = 21915961 is a prime.

It is a super-2 number, since 2×21915969² = 960619394417922, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21915969.

It is not an unprimeable number, because it can be changed into a prime (21915961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3652659 + ... + 3652664.

It is an arithmetic number, because the mean of its divisors is an integer number (7305324).

Almost surely, 2^21915969 is an apocalyptic number.

It is an amenable number.

21915969 is a deficient number, since it is larger than the sum of its proper divisors (7305327).

21915969 is an equidigital number, since it uses as much as digits as its factorization.

21915969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7305326.

The product of its digits is 43740, while the sum is 42.

The square root of 21915969 is about 4681.4494550299. The cubic root of 21915969 is about 279.8467230816.

The spelling of 21915969 in words is "twenty-one million, nine hundred fifteen thousand, nine hundred sixty-nine".