21823057 has 4 divisors (see below), whose sum is σ = 22130496. Its totient is φ = 21515620.

The previous prime is 21823033. The next prime is 21823063. The reversal of 21823057 is 75032812.

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 21823057 - 2¹⁹ = 21298769 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21823027) 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, 153613 + ... + 153754.

It is an arithmetic number, because the mean of its divisors is an integer number (5532624).

Almost surely, 2^21823057 is an apocalyptic number.

It is an amenable number.

21823057 is a deficient number, since it is larger than the sum of its proper divisors (307439).

21823057 is an equidigital number, since it uses as much as digits as its factorization.

21823057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 307438.

The product of its (nonzero) digits is 3360, while the sum is 28.

The square root of 21823057 is about 4671.5154928567. The cubic root of 21823057 is about 279.4506960394.

Adding to 21823057 its reverse (75032812), we get a palindrome (96855869).

The spelling of 21823057 in words is "twenty-one million, eight hundred twenty-three thousand, fifty-seven".