21312501798744 has 512 divisors, whose sum is σ = 67169146060800. Its totient is φ = 6215698944000.

The previous prime is 21312501798689. The next prime is 21312501798751. The reversal of 21312501798744 is 44789710521312.

It is a happy number.

21312501798744 is a `hidden beast` number, since 2 + 1 + 3 + 1 + 2 + 501 + 7 + 98 + 7 + 44 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2911142604 + ... + 2911149924.

It is an arithmetic number, because the mean of its divisors is an integer number (131189738400).

Almost surely, 2^{21312501798744} is an apocalyptic number.

21312501798744 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 21312501798744, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33584573030400).

21312501798744 is an abundant number, since it is smaller than the sum of its proper divisors (45856644262056).

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

21312501798744 is a wasteful number, since it uses less digits than its factorization.

21312501798744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8064 (or 8054 counting only the distinct ones).

The product of its (nonzero) digits is 3386880, while the sum is 54.

The spelling of 21312501798744 in words is "twenty-one trillion, three hundred twelve billion, five hundred one million, seven hundred ninety-eight thousand, seven hundred forty-four".