21642053 has 4 divisors (see below), whose sum is σ = 21657888. Its totient is φ = 21626220.

The previous prime is 21642017. The next prime is 21642067. The reversal of 21642053 is 35024612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21642053 - 2⁸ = 21641797 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21642013) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5651 + ... + 8672.

It is an arithmetic number, because the mean of its divisors is an integer number (5414472).

Almost surely, 2^21642053 is an apocalyptic number.

It is an amenable number.

21642053 is a deficient number, since it is larger than the sum of its proper divisors (15835).

21642053 is a wasteful number, since it uses less digits than its factorization.

21642053 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15834.

The product of its (nonzero) digits is 1440, while the sum is 23.

The square root of 21642053 is about 4652.1019980220. The cubic root of 21642053 is about 278.6759468673.

Adding to 21642053 its reverse (35024612), we get a palindrome (56666665).

The spelling of 21642053 in words is "twenty-one million, six hundred forty-two thousand, fifty-three".