21053057 has 4 divisors (see below), whose sum is σ = 21102336. Its totient is φ = 21003780.

The previous prime is 21053051. The next prime is 21053059. The reversal of 21053057 is 75035012.

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 21053057 - 2⁴ = 21053041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21053051) 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, 23993 + ... + 24854.

It is an arithmetic number, because the mean of its divisors is an integer number (5275584).

Almost surely, 2^21053057 is an apocalyptic number.

It is an amenable number.

21053057 is a deficient number, since it is larger than the sum of its proper divisors (49279).

21053057 is an equidigital number, since it uses as much as digits as its factorization.

21053057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 49278.

The product of its (nonzero) digits is 1050, while the sum is 23.

The square root of 21053057 is about 4588.3610363615. The cubic root of 21053057 is about 276.1245718207.

Adding to 21053057 its reverse (75035012), we get a palindrome (96088069).

The spelling of 21053057 in words is "twenty-one million, fifty-three thousand, fifty-seven".