21791662464 has 384 divisors, whose sum is σ = 70195910400. Its totient is φ = 5946716160.

The previous prime is 21791662441. The next prime is 21791662469. The reversal of 21791662464 is 46426619712.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (384).

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21791662469) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 25972957 + ... + 25973795.

It is an arithmetic number, because the mean of its divisors is an integer number (182801850).

Almost surely, 2^21791662464 is an apocalyptic number.

21791662464 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 21791662464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35097955200).

21791662464 is an abundant number, since it is smaller than the sum of its proper divisors (48404247936).

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

21791662464 is a wasteful number, since it uses less digits than its factorization.

21791662464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 934 (or 911 counting only the distinct ones).

The product of its digits is 870912, while the sum is 48.

The spelling of 21791662464 in words is "twenty-one billion, seven hundred ninety-one million, six hundred sixty-two thousand, four hundred sixty-four".