21936969 has 6 divisors (see below), whose sum is σ = 31686746. Its totient is φ = 14624640.

The previous prime is 21936961. The next prime is 21936973. The reversal of 21936969 is 96963912.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 19686969 + 2250000 = 4437^2 + 1500^2 .

It is not a de Polignac number, because 21936969 - 2³ = 21936961 is a prime.

It is a super-2 number, since 2×21936969² = 962461217813922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21936961) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1218712 + ... + 1218729.

Almost surely, 2^21936969 is an apocalyptic number.

It is an amenable number.

21936969 is a deficient number, since it is larger than the sum of its proper divisors (9749777).

21936969 is a wasteful number, since it uses less digits than its factorization.

21936969 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2437447 (or 2437444 counting only the distinct ones).

The product of its digits is 157464, while the sum is 45.

The square root of 21936969 is about 4683.6918130893. The cubic root of 21936969 is about 279.9360780953.

The spelling of 21936969 in words is "twenty-one million, nine hundred thirty-six thousand, nine hundred sixty-nine".