21456408420 has 72 divisors (see below), whose sum is σ = 65515544640. Its totient is φ = 5683809600.

The previous prime is 21456408403. The next prime is 21456408431. The reversal of 21456408420 is 2480465412.

21456408420 is a `hidden beast` number, since 2 + 1 + 4 + 5 + 640 + 8 + 4 + 2 + 0 = 666.

It is a super-3 number, since 3×21456408420³ (a number of 32 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 367530 + ... + 421889.

It is an arithmetic number, because the mean of its divisors is an integer number (909938120).

Almost surely, 2^21456408420 is an apocalyptic number.

21456408420 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21456408420 is an abundant number, since it is smaller than the sum of its proper divisors (44059136220).

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

21456408420 is a wasteful number, since it uses less digits than its factorization.

21456408420 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 789585 (or 789580 counting only the distinct ones).

The product of its (nonzero) digits is 61440, while the sum is 36.

The spelling of 21456408420 in words is "twenty-one billion, four hundred fifty-six million, four hundred eight thousand, four hundred twenty".