21321612240 has 80 divisors (see below), whose sum is σ = 67002491328. Its totient is φ = 5607871488.

The previous prime is 21321612239. The next prime is 21321612241. The reversal of 21321612240 is 4221612312.

It is an interprime number because it is at equal distance from previous prime (21321612239) and next prime (21321612241).

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×21321612240² (a number of 21 digits) contains 22 as substring.

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

It is a self number, because there is not a number n which added to its sum of digits gives 21321612240.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321612241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 590974 + ... + 626013.

Almost surely, 2^21321612240 is an apocalyptic number.

21321612240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21321612240 is an abundant number, since it is smaller than the sum of its proper divisors (45680879088).

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

21321612240 is a wasteful number, since it uses less digits than its factorization.

21321612240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1217076 (or 1217070 counting only the distinct ones).

The product of its (nonzero) digits is 1152, while the sum is 24.

It can be divided in two parts, 213216 and 12240, that added together give a triangular number (225456 = T₆₇₁).

The spelling of 21321612240 in words is "twenty-one billion, three hundred twenty-one million, six hundred twelve thousand, two hundred forty".