21557810246418 has 128 divisors (see below), whose sum is σ = 48549541847040. Its totient is φ = 7090005556800.

The previous prime is 21557810246369. The next prime is 21557810246431. The reversal of 21557810246418 is 81464201875512.

21557810246418 is a `hidden beast` number, since 2 + 1 + 5 + 5 + 78 + 102 + 464 + 1 + 8 = 666.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1752518868 + ... + 1752531168.

It is an arithmetic number, because the mean of its divisors is an integer number (379293295680).

Almost surely, 2^{21557810246418} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21557810246418, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24274770923520).

21557810246418 is an abundant number, since it is smaller than the sum of its proper divisors (26991731600622).

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

21557810246418 is a wasteful number, since it uses less digits than its factorization.

21557810246418 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13549 (or 13543 counting only the distinct ones).

The product of its (nonzero) digits is 4300800, while the sum is 54.

The spelling of 21557810246418 in words is "twenty-one trillion, five hundred fifty-seven billion, eight hundred ten million, two hundred forty-six thousand, four hundred eighteen".