21037057 has 4 divisors (see below), whose sum is σ = 21047040. Its totient is φ = 21027076.

The previous prime is 21037021. The next prime is 21037061. The reversal of 21037057 is 75073012.

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, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21037057 - 2⁷ = 21036929 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21037657) 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, 457 + ... + 6502.

It is an arithmetic number, because the mean of its divisors is an integer number (5261760).

It is a Proth number, since it is equal to 321 ⋅ 2¹⁶ + 1 and 321 < 2¹⁶.

Almost surely, 2^21037057 is an apocalyptic number.

It is an amenable number.

21037057 is a deficient number, since it is larger than the sum of its proper divisors (9983).

21037057 is an equidigital number, since it uses as much as digits as its factorization.

21037057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9982.

The product of its (nonzero) digits is 1470, while the sum is 25.

The square root of 21037057 is about 4586.6171630080. The cubic root of 21037057 is about 276.0546039482.

The spelling of 21037057 in words is "twenty-one million, thirty-seven thousand, fifty-seven".