21557479814640 has 1920 divisors, whose sum is σ = 98682781040640. Its totient is φ = 4201379020800.

The previous prime is 21557479814617. The next prime is 21557479814653. The reversal of 21557479814640 is 4641897475512.

It is a happy number.

21557479814640 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 7 + 479 + 81 + 46 + 40 = 666.

It is a super-2 number, since 2×21557479814640² (a number of 27 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 18409461255 + ... + 18409462425.

It is an arithmetic number, because the mean of its divisors is an integer number (51397281792).

Almost surely, 2^{21557479814640} is an apocalyptic number.

21557479814640 is a gapful number since it is divisible by the number (20) 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 21557479814640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (49341390520320).

21557479814640 is an abundant number, since it is smaller than the sum of its proper divisors (77125301226000).

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

21557479814640 is a wasteful number, since it uses less digits than its factorization.

21557479814640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1628 (or 1599 counting only the distinct ones).

The product of its (nonzero) digits is 67737600, while the sum is 63.

The spelling of 21557479814640 in words is "twenty-one trillion, five hundred fifty-seven billion, four hundred seventy-nine million, eight hundred fourteen thousand, six hundred forty".