61631891802 has 144 divisors (see below), whose sum is σ = 151065971784. Its totient is φ = 18047059200.

The previous prime is 61631891773. The next prime is 61631891803. The reversal of 61631891802 is 20819813616.

61631891802 is a `hidden beast` number, since 6 + 1 + 631 + 8 + 9 + 1 + 8 + 0 + 2 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 46032131601 + 15599760201 = 214551^2 + 124899^2 .

It is not an unprimeable number, because it can be changed into a prime (61631891803) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 13715068 + ... + 13719560.

Almost surely, 2^61631891802 is an apocalyptic number.

61631891802 is a gapful number since it is divisible by the number (62) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 61631891802, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (75532985892).

61631891802 is an abundant number, since it is smaller than the sum of its proper divisors (89434079982).

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

61631891802 is a wasteful number, since it uses less digits than its factorization.

61631891802 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4637 (or 4603 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The spelling of 61631891802 in words is "sixty-one billion, six hundred thirty-one million, eight hundred ninety-one thousand, eight hundred two".