21211870464 has 324 divisors, whose sum is σ = 64750197876. Its totient is φ = 6933454848.

The previous prime is 21211870457. The next prime is 21211870481. The reversal of 21211870464 is 46407811212.

It is a happy number.

21211870464 is a `hidden beast` number, since 2 + 12 + 1 + 187 + 0 + 464 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 16131032064 + 5080838400 = 127008^2 + 71280^2 .

It is a tau number, because it is divible by the number of its divisors (324).

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 122611882 + ... + 122612054.

Almost surely, 2^21211870464 is an apocalyptic number.

21211870464 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21211870464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32375098938).

21211870464 is an abundant number, since it is smaller than the sum of its proper divisors (43538327412).

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

21211870464 is an frugal number, since it uses more digits than its factorization.

21211870464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 286 (or 251 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The spelling of 21211870464 in words is "twenty-one billion, two hundred eleven million, eight hundred seventy thousand, four hundred sixty-four".