7985661957 has 72 divisors (see below), whose sum is σ = 15300446616. Its totient is φ = 3964391424.

The previous prime is 7985661949. The next prime is 7985661979. The reversal of 7985661957 is 7591665897.

7985661957 is a `hidden beast` number, since 7 + 9 + 8 + 5 + 6 + 619 + 5 + 7 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 1918965636 + 6066696321 = 43806^2 + 77889^2 .

It is not a de Polignac number, because 7985661957 - 2³ = 7985661949 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a junction number, because it is equal to n+sod(n) for n = 7985661894 and 7985661903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7985661757) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 56493 + ... + 138429.

It is an arithmetic number, because the mean of its divisors is an integer number (212506203).

Almost surely, 2^7985661957 is an apocalyptic number.

It is an amenable number.

7985661957 is a deficient number, since it is larger than the sum of its proper divisors (7314784659).

7985661957 is a wasteful number, since it uses less digits than its factorization.

7985661957 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81987 (or 81977 counting only the distinct ones).

The product of its digits is 28576800, while the sum is 63.

The square root of 7985661957 is about 89362.5310574852. The cubic root of 7985661957 is about 1998.8044485541.

The spelling of 7985661957 in words is "seven billion, nine hundred eighty-five million, six hundred sixty-one thousand, nine hundred fifty-seven".