61722278388 has 18 divisors (see below), whose sum is σ = 156020203794. Its totient is φ = 20574092784.

The previous prime is 61722278357. The next prime is 61722278393. The reversal of 61722278388 is 88387222716.

61722278388 is a `hidden beast` number, since 6 + 172 + 22 + 78 + 388 = 666.

It can be written as a sum of positive squares in only one way, i.e., 50944101264 + 10778177124 = 225708^2 + 103818^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 857253831 + ... + 857253902.

Almost surely, 2^61722278388 is an apocalyptic number.

It is an amenable number.

61722278388 is an abundant number, since it is smaller than the sum of its proper divisors (94297925406).

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

61722278388 is a wasteful number, since it uses less digits than its factorization.

61722278388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1714507743 (or 1714507738 counting only the distinct ones).

The product of its digits is 3612672, while the sum is 54.

It can be divided in two parts, 617222 and 78388, that added together give a triangular number (695610 = T₁₁₇₉).

The spelling of 61722278388 in words is "sixty-one billion, seven hundred twenty-two million, two hundred seventy-eight thousand, three hundred eighty-eight".