61500377781 has 12 divisors (see below), whose sum is σ = 89904167808. Its totient is φ = 40506272424.

The previous prime is 61500377723. The next prime is 61500377789. The reversal of 61500377781 is 18777300516.

61500377781 is a `hidden beast` number, since 6 + 1 + 500 + 3 + 77 + 78 + 1 = 666.

It is not a de Polignac number, because 61500377781 - 2⁶ = 61500377717 is a prime.

It is a super-2 number, since 2×61500377781² (a number of 22 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61500377789) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 41164165 + ... + 41165658.

It is an arithmetic number, because the mean of its divisors is an integer number (7492013984).

Almost surely, 2^61500377781 is an apocalyptic number.

It is an amenable number.

61500377781 is a deficient number, since it is larger than the sum of its proper divisors (28403790027).

61500377781 is a wasteful number, since it uses less digits than its factorization.

61500377781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82329912 (or 82329909 counting only the distinct ones).

The product of its (nonzero) digits is 246960, while the sum is 45.

The spelling of 61500377781 in words is "sixty-one billion, five hundred million, three hundred seventy-seven thousand, seven hundred eighty-one".