21465312 has 48 divisors (see below), whose sum is σ = 61471872. Its totient is φ = 6504320.

The previous prime is 21465289. The next prime is 21465313. The reversal of 21465312 is 21356412.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21465313) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9108 + ... + 11219.

It is an arithmetic number, because the mean of its divisors is an integer number (1280664).

Almost surely, 2^21465312 is an apocalyptic number.

21465312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21465312 is an abundant number, since it is smaller than the sum of its proper divisors (40006560).

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

21465312 is a wasteful number, since it uses less digits than its factorization.

21465312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20351 (or 20343 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21465312 is about 4633.0672345650. The cubic root of 21465312 is about 277.9152649641.

Subtracting from 21465312 its reverse (21356412), we obtain a square (108900 = 330²).

The spelling of 21465312 in words is "twenty-one million, four hundred sixty-five thousand, three hundred twelve".