61660769781 has 16 divisors (see below), whose sum is σ = 88560308480. Its totient is φ = 37935760320.

The previous prime is 61660769747. The next prime is 61660769809. The reversal of 61660769781 is 18796706616.

It is not a de Polignac number, because 61660769781 - 2²¹ = 61658672629 is a prime.

It is a super-2 number, since 2×61660769781² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (61660769701) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 31966 + ... + 352623.

It is an arithmetic number, because the mean of its divisors is an integer number (5535019280).

Almost surely, 2^61660769781 is an apocalyptic number.

It is an amenable number.

61660769781 is a deficient number, since it is larger than the sum of its proper divisors (26899538699).

61660769781 is a wasteful number, since it uses less digits than its factorization.

61660769781 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 388716.

The product of its (nonzero) digits is 4572288, while the sum is 57.

The spelling of 61660769781 in words is "sixty-one billion, six hundred sixty million, seven hundred sixty-nine thousand, seven hundred eighty-one".