21810057 has 16 divisors (see below), whose sum is σ = 30004800. Its totient is φ = 14081472.

The previous prime is 21810053. The next prime is 21810071. The reversal of 21810057 is 75001812.

It is not a de Polignac number, because 21810057 - 2² = 21810053 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21810053) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38458 + ... + 39020.

It is an arithmetic number, because the mean of its divisors is an integer number (1875300).

Almost surely, 2^21810057 is an apocalyptic number.

It is an amenable number.

21810057 is a deficient number, since it is larger than the sum of its proper divisors (8194743).

21810057 is a wasteful number, since it uses less digits than its factorization.

21810057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 952.

The product of its (nonzero) digits is 560, while the sum is 24.

The square root of 21810057 is about 4670.1238741601. The cubic root of 21810057 is about 279.3951954031.

Adding to 21810057 its reverse (75001812), we get a palindrome (96811869).

The spelling of 21810057 in words is "twenty-one million, eight hundred ten thousand, fifty-seven".