661113933637 has 4 divisors (see below), whose sum is σ = 661151495340. Its totient is φ = 661076371936.

The previous prime is 661113933607. The next prime is 661113933643. The reversal of 661113933637 is 736339311166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 736339311166 = 2 ⋅368169655583.

It can be written as a sum of positive squares in 2 ways, for example, as 224416323076 + 436697610561 = 473726^2 + 660831^2 .

It is a cyclic number.

It is not a de Polignac number, because 661113933637 - 2²³ = 661105545029 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661113933607) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18754438 + ... + 18789655.

It is an arithmetic number, because the mean of its divisors is an integer number (165287873835).

Almost surely, 2^661113933637 is an apocalyptic number.

It is an amenable number.

661113933637 is a deficient number, since it is larger than the sum of its proper divisors (37561703).

661113933637 is a wasteful number, since it uses less digits than its factorization.

661113933637 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37561702.

The product of its digits is 1102248, while the sum is 49.

The spelling of 661113933637 in words is "six hundred sixty-one billion, one hundred thirteen million, nine hundred thirty-three thousand, six hundred thirty-seven".