21151308 has 12 divisors (see below), whose sum is σ = 49353080. Its totient is φ = 7050432.

The previous prime is 21151307. The next prime is 21151343. The reversal of 21151308 is 80315112.

It is a tau number, because it is divible by the number of its divisors (12).

It is a super-2 number, since 2×21151308² = 894755660221728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21151303) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 881293 + ... + 881316.

Almost surely, 2^21151308 is an apocalyptic number.

It is an amenable number.

21151308 is an abundant number, since it is smaller than the sum of its proper divisors (28201772).

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

21151308 is a wasteful number, since it uses less digits than its factorization.

21151308 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1762616 (or 1762614 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 21.

The square root of 21151308 is about 4599.0551203481. The cubic root of 21151308 is about 276.5534473273.

The spelling of 21151308 in words is "twenty-one million, one hundred fifty-one thousand, three hundred eight".