21615566102440 has 128 divisors (see below), whose sum is σ = 51183625248000. Its totient is φ = 8203574937600.

The previous prime is 21615566102423. The next prime is 21615566102441. The reversal of 21615566102440 is 4420166551612.

It is not an unprimeable number, because it can be changed into a prime (21615566102441) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 190959460 + ... + 191072620.

It is an arithmetic number, because the mean of its divisors is an integer number (399872072250).

Almost surely, 2^{21615566102440} is an apocalyptic number.

21615566102440 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 21615566102440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25591812624000).

21615566102440 is an abundant number, since it is smaller than the sum of its proper divisors (29568059145560).

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

21615566102440 is a wasteful number, since it uses less digits than its factorization.

21615566102440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116051 (or 116047 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 43.

The spelling of 21615566102440 in words is "twenty-one trillion, six hundred fifteen billion, five hundred sixty-six million, one hundred two thousand, four hundred forty".