21257994 has 16 divisors (see below), whose sum is σ = 42677280. Its totient is φ = 7059120.

The previous prime is 21257993. The next prime is 21258001. The reversal of 21257994 is 49975212.

It is not an unprimeable number, because it can be changed into a prime (21257993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4972 + ... + 8199.

It is an arithmetic number, because the mean of its divisors is an integer number (2667330).

Almost surely, 2^21257994 is an apocalyptic number.

21257994 is an abundant number, since it is smaller than the sum of its proper divisors (21419286).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21257994 is a wasteful number, since it uses less digits than its factorization.

21257994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13445.

The product of its digits is 45360, while the sum is 39.

The square root of 21257994 is about 4610.6392181562. The cubic root of 21257994 is about 277.0176410544.

The spelling of 21257994 in words is "twenty-one million, two hundred fifty-seven thousand, nine hundred ninety-four".