21051308 has 6 divisors (see below), whose sum is σ = 36839796. Its totient is φ = 10525652.

The previous prime is 21051271. The next prime is 21051311. The reversal of 21051308 is 80315012.

It is a self number, because there is not a number n which added to its sum of digits gives 21051308.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2631410 + ... + 2631417.

It is an arithmetic number, because the mean of its divisors is an integer number (6139966).

Almost surely, 2^21051308 is an apocalyptic number.

It is an amenable number.

21051308 is a deficient number, since it is larger than the sum of its proper divisors (15788488).

21051308 is a wasteful number, since it uses less digits than its factorization.

21051308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5262831 (or 5262829 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 21051308 is about 4588.1704414723. The cubic root of 21051308 is about 276.1169251838.

The spelling of 21051308 in words is "twenty-one million, fifty-one thousand, three hundred eight".