21251704 has 16 divisors (see below), whose sum is σ = 39902400. Its totient is φ = 10611072.

The previous prime is 21251689. The next prime is 21251719. The reversal of 21251704 is 40715212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21251689) and next prime (21251719).

It is a plaindrome in base 16.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6457 + ... + 9175.

It is an arithmetic number, because the mean of its divisors is an integer number (2493900).

Almost surely, 2^21251704 is an apocalyptic number.

It is an amenable number.

21251704 is a deficient number, since it is larger than the sum of its proper divisors (18650696).

21251704 is a wasteful number, since it uses less digits than its factorization.

21251704 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3702 (or 3698 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 21251704 is about 4609.9570496915. The cubic root of 21251704 is about 276.9903162302.

Adding to 21251704 its reverse (40715212), we get a palindrome (61966916).

The spelling of 21251704 in words is "twenty-one million, two hundred fifty-one thousand, seven hundred four".