61631720 has 64 divisors (see below), whose sum is σ = 149437440. Its totient is φ = 22809600.

The previous prime is 61631659. The next prime is 61631723. The reversal of 61631720 is 2713616.

It is a hoax number, since the sum of its digits (26) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 61631720.

It is not an unprimeable number, because it can be changed into a prime (61631723) 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, 27440 + ... + 29600.

It is an arithmetic number, because the mean of its divisors is an integer number (2334960).

Almost surely, 2^61631720 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 61631720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (74718720).

61631720 is an abundant number, since it is smaller than the sum of its proper divisors (87805720).

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

61631720 is a wasteful number, since it uses less digits than its factorization.

61631720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2226 (or 2222 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 26.

The square root of 61631720 is about 7850.5872391815. The cubic root of 61631720 is about 395.0039416367.

The spelling of 61631720 in words is "sixty-one million, six hundred thirty-one thousand, seven hundred twenty".