21086057 has 4 divisors (see below), whose sum is σ = 21290880. Its totient is φ = 20881236.

The previous prime is 21086027. The next prime is 21086089. The reversal of 21086057 is 75068012.

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 21086057 - 2⁶ = 21085993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21086017) 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, 102257 + ... + 102462.

It is an arithmetic number, because the mean of its divisors is an integer number (5322720).

Almost surely, 2^21086057 is an apocalyptic number.

It is an amenable number.

21086057 is a deficient number, since it is larger than the sum of its proper divisors (204823).

21086057 is a wasteful number, since it uses less digits than its factorization.

21086057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204822.

The product of its (nonzero) digits is 3360, while the sum is 29.

The square root of 21086057 is about 4591.9556835841. The cubic root of 21086057 is about 276.2687686790.

The spelling of 21086057 in words is "twenty-one million, eighty-six thousand, fifty-seven".