61621776720 has 180 divisors, whose sum is σ = 240733782900. Its totient is φ = 14084969472.

The previous prime is 61621776661. The next prime is 61621776761. The reversal of 61621776720 is 2767712616.

61621776720 is a `hidden beast` number, since 616 + 2 + 1 + 7 + 7 + 6 + 7 + 20 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 44029468224 + 17592308496 = 209832^2 + 132636^2 .

It is a tau number, because it is divible by the number of its divisors (180).

It is a super-2 number, since 2×61621776720² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 838045 + ... + 908604.

It is an arithmetic number, because the mean of its divisors is an integer number (1337409905).

Almost surely, 2^61621776720 is an apocalyptic number.

61621776720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

61621776720 is an abundant number, since it is smaller than the sum of its proper divisors (179112006180).

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

61621776720 is a wasteful number, since it uses less digits than its factorization.

61621776720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1746682 (or 1746666 counting only the distinct ones).

The product of its (nonzero) digits is 296352, while the sum is 45.

The spelling of 61621776720 in words is "sixty-one billion, six hundred twenty-one million, seven hundred seventy-six thousand, seven hundred twenty".