61555712220 has 36 divisors (see below), whose sum is σ = 186718994280. Its totient is φ = 16414856544.

The previous prime is 61555712209. The next prime is 61555712227. The reversal of 61555712220 is 2221755516.

61555712220 is a `hidden beast` number, since 61 + 5 + 5 + 571 + 2 + 2 + 20 = 666.

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

It is a super-2 number, since 2×61555712220² (a number of 22 digits) contains 22 as substring.

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 (61555712227) 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, 170987910 + ... + 170988269.

It is an arithmetic number, because the mean of its divisors is an integer number (5186638730).

Almost surely, 2^61555712220 is an apocalyptic number.

61555712220 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

61555712220 is an abundant number, since it is smaller than the sum of its proper divisors (125163282060).

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

61555712220 is a wasteful number, since it uses less digits than its factorization.

61555712220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 341976194 (or 341976189 counting only the distinct ones).

The product of its (nonzero) digits is 42000, while the sum is 36.

The spelling of 61555712220 in words is "sixty-one billion, five hundred fifty-five million, seven hundred twelve thousand, two hundred twenty".