121557713640 has 128 divisors (see below), whose sum is σ = 397961596800. Its totient is φ = 29458437120.

The previous prime is 121557713579. The next prime is 121557713663. The reversal of 121557713640 is 46317755121.

It is a junction number, because it is equal to n+sod(n) for n = 121557713592 and 121557713601.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4279806 + ... + 4308114.

It is an arithmetic number, because the mean of its divisors is an integer number (3109074975).

Almost surely, 2^121557713640 is an apocalyptic number.

121557713640 is a gapful number since it is divisible by the number (10) 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 121557713640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (198980798400).

121557713640 is an abundant number, since it is smaller than the sum of its proper divisors (276403883160).

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

121557713640 is a wasteful number, since it uses less digits than its factorization.

121557713640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31587 (or 31583 counting only the distinct ones).

The product of its (nonzero) digits is 176400, while the sum is 42.

The spelling of 121557713640 in words is "one hundred twenty-one billion, five hundred fifty-seven million, seven hundred thirteen thousand, six hundred forty".