61515515880 has 1024 divisors, whose sum is σ = 265583001600. Its totient is φ = 12317184000.

The previous prime is 61515515837. The next prime is 61515515891. The reversal of 61515515880 is 8851551516.

61515515880 is a `hidden beast` number, since 6 + 1 + 5 + 15 + 51 + 588 + 0 = 666.

61515515880 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 185847315 + ... + 185847645.

It is an arithmetic number, because the mean of its divisors is an integer number (259358400).

Almost surely, 2^61515515880 is an apocalyptic number.

61515515880 is a gapful number since it is divisible by the number (60) 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 61515515880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132791500800).

61515515880 is an abundant number, since it is smaller than the sum of its proper divisors (204067485720).

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

61515515880 is a wasteful number, since it uses less digits than its factorization.

61515515880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 463 (or 453 counting only the distinct ones).

The product of its (nonzero) digits is 240000, while the sum is 45.

The spelling of 61515515880 in words is "sixty-one billion, five hundred fifteen million, five hundred fifteen thousand, eight hundred eighty".