661131537 has 24 divisors (see below), whose sum is σ = 970546752. Its totient is φ = 400018080.

The previous prime is 661131517. The next prime is 661131571. The reversal of 661131537 is 735131166.

It is a happy number.

It is not a de Polignac number, because 661131537 - 2¹⁰ = 661130513 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a junction number, because it is equal to n+sod(n) for n = 661131498 and 661131507.

It is not an unprimeable number, because it can be changed into a prime (661131517) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 297643 + ... + 299855.

It is an arithmetic number, because the mean of its divisors is an integer number (40439448).

Almost surely, 2^661131537 is an apocalyptic number.

It is an amenable number.

661131537 is a deficient number, since it is larger than the sum of its proper divisors (309415215).

661131537 is a wasteful number, since it uses less digits than its factorization.

661131537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3061 (or 3050 counting only the distinct ones).

The product of its digits is 11340, while the sum is 33.

The square root of 661131537 is about 25712.4782352849. The cubic root of 661131537 is about 871.1560520122.

The spelling of 661131537 in words is "six hundred sixty-one million, one hundred thirty-one thousand, five hundred thirty-seven".