21521308 has 6 divisors (see below), whose sum is σ = 37662296. Its totient is φ = 10760652.

The previous prime is 21521299. The next prime is 21521317. The reversal of 21521308 is 80312512.

It is an interprime number because it is at equal distance from previous prime (21521299) and next prime (21521317).

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2690160 + ... + 2690167.

Almost surely, 2^21521308 is an apocalyptic number.

It is an amenable number.

21521308 is a deficient number, since it is larger than the sum of its proper divisors (16140988).

21521308 is a wasteful number, since it uses less digits than its factorization.

21521308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5380331 (or 5380329 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 21521308 is about 4639.1063794658. The cubic root of 21521308 is about 278.1567185641.

The spelling of 21521308 in words is "twenty-one million, five hundred twenty-one thousand, three hundred eight".