61631640 has 192 divisors, whose sum is σ = 235460160. Its totient is φ = 13685760.

The previous prime is 61631639. The next prime is 61631659. The reversal of 61631640 is 4613616.

61631640 is a `hidden beast` number, since 6 + 16 + 3 + 1 + 640 = 666.

61631640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

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 47 ways as a sum of consecutive naturals, for example, 92910 + ... + 93570.

It is an arithmetic number, because the mean of its divisors is an integer number (1226355).

Almost surely, 2^61631640 is an apocalyptic number.

61631640 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 61631640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117730080).

61631640 is an abundant number, since it is smaller than the sum of its proper divisors (173828520).

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

61631640 is a wasteful number, since it uses less digits than its factorization.

61631640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 722 (or 715 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 27.

The square root of 61631640 is about 7850.5821440196. The cubic root of 61631640 is about 395.0037707272.

The spelling of 61631640 in words is "sixty-one million, six hundred thirty-one thousand, six hundred forty".