21513308 has 12 divisors (see below), whose sum is σ = 37920120. Its totient is φ = 10678992.

The previous prime is 21513307. The next prime is 21513329. The reversal of 21513308 is 80331512.

It is a super-2 number, since 2×21513308² = 925644842205728, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21513307) 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, 18791 + ... + 19902.

It is an arithmetic number, because the mean of its divisors is an integer number (3160010).

Almost surely, 2^21513308 is an apocalyptic number.

It is an amenable number.

21513308 is a deficient number, since it is larger than the sum of its proper divisors (16406812).

21513308 is a wasteful number, since it uses less digits than its factorization.

21513308 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38836 (or 38834 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 23.

The square root of 21513308 is about 4638.2440642985. The cubic root of 21513308 is about 278.1222483926.

The spelling of 21513308 in words is "twenty-one million, five hundred thirteen thousand, three hundred eight".