21249764 has 12 divisors (see below), whose sum is σ = 37455600. Its totient is φ = 10548168.

The previous prime is 21249751. The next prime is 21249773. The reversal of 21249764 is 46794212.

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, 18554 + ... + 19665.

It is an arithmetic number, because the mean of its divisors is an integer number (3121300).

Almost surely, 2^21249764 is an apocalyptic number.

It is an amenable number.

21249764 is a deficient number, since it is larger than the sum of its proper divisors (16205836).

21249764 is a wasteful number, since it uses less digits than its factorization.

21249764 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38362 (or 38360 counting only the distinct ones).

The product of its digits is 24192, while the sum is 35.

The square root of 21249764 is about 4609.7466307813. The cubic root of 21249764 is about 276.9818874540.

The spelling of 21249764 in words is "twenty-one million, two hundred forty-nine thousand, seven hundred sixty-four".