21632643 has 16 divisors (see below), whose sum is σ = 32732160. Its totient is φ = 14114088.

The previous prime is 21632641. The next prime is 21632647. The reversal of 21632643 is 34623612.

21632643 is a `hidden beast` number, since 2 + 16 + 3 + 2 + 643 = 666.

It is not a de Polignac number, because 21632643 - 2¹ = 21632641 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21632641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7255 + ... + 9792.

It is an arithmetic number, because the mean of its divisors is an integer number (2045760).

Almost surely, 2^21632643 is an apocalyptic number.

21632643 is a deficient number, since it is larger than the sum of its proper divisors (11099517).

21632643 is a wasteful number, since it uses less digits than its factorization.

21632643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17103 (or 17097 counting only the distinct ones).

The product of its digits is 5184, while the sum is 27.

The square root of 21632643 is about 4651.0905172873. The cubic root of 21632643 is about 278.6355514264.

The spelling of 21632643 in words is "twenty-one million, six hundred thirty-two thousand, six hundred forty-three".