61815810 has 64 divisors (see below), whose sum is σ = 173187072. Its totient is φ = 13826496.

The previous prime is 61815781. The next prime is 61815821. The reversal of 61815810 is 1851816.

It is a happy number.

61815810 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×61815810² = 7642388731912200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6739 + ... + 13001.

It is an arithmetic number, because the mean of its divisors is an integer number (2706048).

Almost surely, 2^61815810 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61815810, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (86593536).

61815810 is an abundant number, since it is smaller than the sum of its proper divisors (111371262).

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

61815810 is a wasteful number, since it uses less digits than its factorization.

61815810 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6327.

The product of its (nonzero) digits is 1920, while the sum is 30.

The square root of 61815810 is about 7862.3030976934. The cubic root of 61815810 is about 395.3968345382.

The spelling of 61815810 in words is "sixty-one million, eight hundred fifteen thousand, eight hundred ten".