61911521172 has 36 divisors (see below), whose sum is σ = 160728261876. Its totient is φ = 20079411840.

The previous prime is 61911521171. The next prime is 61911521173. The reversal of 61911521172 is 27112511916.

61911521172 is a `hidden beast` number, since 61 + 9 + 1 + 1 + 521 + 1 + 72 = 666.

It is an interprime number because it is at equal distance from previous prime (61911521171) and next prime (61911521173).

It can be written as a sum of positive squares in 2 ways, for example, as 54584845956 + 7326675216 = 233634^2 + 85596^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61911521171) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 23238729 + ... + 23241392.

It is an arithmetic number, because the mean of its divisors is an integer number (4464673941).

Almost surely, 2^61911521172 is an apocalyptic number.

It is an amenable number.

61911521172 is an abundant number, since it is smaller than the sum of its proper divisors (98816740704).

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

61911521172 is a wasteful number, since it uses less digits than its factorization.

61911521172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46480168 (or 46480163 counting only the distinct ones).

The product of its digits is 7560, while the sum is 36.

The spelling of 61911521172 in words is "sixty-one billion, nine hundred eleven million, five hundred twenty-one thousand, one hundred seventy-two".