21371643 has 12 divisors (see below), whose sum is σ = 30990960. Its totient is φ = 14192016.

The previous prime is 21371627. The next prime is 21371653. The reversal of 21371643 is 34617312.

21371643 is a `hidden beast` number, since 2 + 13 + 7 + 1 + 643 = 666.

It is not a de Polignac number, because 21371643 - 2⁴ = 21371627 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21371653) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2148 + ... + 6881.

It is an arithmetic number, because the mean of its divisors is an integer number (2582580).

Almost surely, 2^21371643 is an apocalyptic number.

21371643 is a deficient number, since it is larger than the sum of its proper divisors (9619317).

21371643 is a wasteful number, since it uses less digits than its factorization.

21371643 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9298 (or 9295 counting only the distinct ones).

The product of its digits is 3024, while the sum is 27.

The square root of 21371643 is about 4622.9474364306. The cubic root of 21371643 is about 277.5104257101.

Adding to 21371643 its reverse (34617312), we get a palindrome (55988955).

The spelling of 21371643 in words is "twenty-one million, three hundred seventy-one thousand, six hundred forty-three".