21642943 has 8 divisors (see below), whose sum is σ = 25104512. Its totient is φ = 18273816.

The previous prime is 21642941. The next prime is 21642949. The reversal of 21642943 is 34924612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21642943 - 2¹ = 21642941 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642941) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22605 + ... + 23542.

It is an arithmetic number, because the mean of its divisors is an integer number (3138064).

Almost surely, 2^21642943 is an apocalyptic number.

21642943 is a deficient number, since it is larger than the sum of its proper divisors (3461569).

21642943 is an equidigital number, since it uses as much as digits as its factorization.

21642943 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46221.

The product of its digits is 10368, while the sum is 31.

The square root of 21642943 is about 4652.1976527229. The cubic root of 21642943 is about 278.6797668714.

The spelling of 21642943 in words is "twenty-one million, six hundred forty-two thousand, nine hundred forty-three".