61815520 has 96 divisors (see below), whose sum is σ = 159268032. Its totient is φ = 22536192.

The previous prime is 61815517. The next prime is 61815521. The reversal of 61815520 is 2551816.

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61815521) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 234909 + ... + 235171.

It is an arithmetic number, because the mean of its divisors is an integer number (1659042).

Almost surely, 2^61815520 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61815520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (79634016).

61815520 is an abundant number, since it is smaller than the sum of its proper divisors (97452512).

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

61815520 is a wasteful number, since it uses less digits than its factorization.

61815520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404 (or 396 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 28.

The square root of 61815520 is about 7862.2846552386. The cubic root of 61815520 is about 395.3962162215.

The spelling of 61815520 in words is "sixty-one million, eight hundred fifteen thousand, five hundred twenty".