21621369 has 48 divisors (see below), whose sum is σ = 37044224. Its totient is φ = 10977120.

The previous prime is 21621337. The next prime is 21621371. The reversal of 21621369 is 96312612.

It is not a de Polignac number, because 21621369 - 2⁵ = 21621337 is a prime.

It is a super-2 number, since 2×21621369² = 934967194868322, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21621329) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 170184 + ... + 170310.

Almost surely, 2^21621369 is an apocalyptic number.

It is an amenable number.

21621369 is a deficient number, since it is larger than the sum of its proper divisors (15422855).

21621369 is a wasteful number, since it uses less digits than its factorization.

21621369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 226 (or 215 counting only the distinct ones).

The product of its digits is 3888, while the sum is 30.

The square root of 21621369 is about 4649.8783855064. The cubic root of 21621369 is about 278.5871387402.

The spelling of 21621369 in words is "twenty-one million, six hundred twenty-one thousand, three hundred sixty-nine".