21621416 has 16 divisors (see below), whose sum is σ = 42925140. Its totient is φ = 10174720.

The previous prime is 21621409. The next prime is 21621421. The reversal of 21621416 is 61412612.

It can be written as a sum of positive squares in 2 ways, for example, as 21585316 + 36100 = 4646^2 + 190^2 .

It is a junction number, because it is equal to n+sod(n) for n = 21621391 and 21621400.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 79355 + ... + 79626.

Almost surely, 2^21621416 is an apocalyptic number.

It is an amenable number.

21621416 is a deficient number, since it is larger than the sum of its proper divisors (21303724).

21621416 is a wasteful number, since it uses less digits than its factorization.

21621416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 159004 (or 159000 counting only the distinct ones).

The product of its digits is 576, while the sum is 23.

The square root of 21621416 is about 4649.8834393993. The cubic root of 21621416 is about 278.5873406020.

The spelling of 21621416 in words is "twenty-one million, six hundred twenty-one thousand, four hundred sixteen".