21115969 has 8 divisors (see below), whose sum is σ = 24372288. Its totient is φ = 17919600.

The previous prime is 21115961. The next prime is 21115993. The reversal of 21115969 is 96951112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21115969 - 2³ = 21115961 is a prime.

It is a super-2 number, since 2×21115969² = 891768293617922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115961) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14227 + ... + 15640.

It is an arithmetic number, because the mean of its divisors is an integer number (3046536).

Almost surely, 2^21115969 is an apocalyptic number.

It is an amenable number.

21115969 is a deficient number, since it is larger than the sum of its proper divisors (3256319).

21115969 is a wasteful number, since it uses less digits than its factorization.

21115969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29975.

The product of its digits is 4860, while the sum is 34.

The square root of 21115969 is about 4595.2115294075. The cubic root of 21115969 is about 276.3993422759.

The spelling of 21115969 in words is "twenty-one million, one hundred fifteen thousand, nine hundred sixty-nine".