61515044864 has 384 divisors, whose sum is σ = 160619397120. Its totient is φ = 22889889792.

The previous prime is 61515044863. The next prime is 61515044923. The reversal of 61515044864 is 46844051516.

It is a happy number.

It is a super-3 number, since 3×61515044864³ (a number of 33 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61515044863) 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, 484370369 + ... + 484370495.

It is an arithmetic number, because the mean of its divisors is an integer number (418279680).

Almost surely, 2^61515044864 is an apocalyptic number.

61515044864 is a gapful number since it is divisible by the number (64) 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 61515044864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (80309698560).

61515044864 is an abundant number, since it is smaller than the sum of its proper divisors (99104352256).

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

61515044864 is a wasteful number, since it uses less digits than its factorization.

61515044864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 305 (or 285 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 44.

The spelling of 61515044864 in words is "sixty-one billion, five hundred fifteen million, forty-four thousand, eight hundred sixty-four".