661442131 has 12 divisors (see below), whose sum is σ = 770669640. Its totient is φ = 566039040.

The previous prime is 661442113. The next prime is 661442143. The reversal of 661442131 is 131244166.

It is a de Polignac number, because none of the positive numbers 2^k-661442131 is a prime.

It is a super-2 number, since 2×661442131² = 875011385323642322, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 661442131.

It is not an unprimeable number, because it can be changed into a prime (661442531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20880 + ... + 41938.

It is an arithmetic number, because the mean of its divisors is an integer number (64222470).

Almost surely, 2^661442131 is an apocalyptic number.

661442131 is a deficient number, since it is larger than the sum of its proper divisors (109227509).

661442131 is a wasteful number, since it uses less digits than its factorization.

661442131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21714 (or 21707 counting only the distinct ones).

The product of its digits is 3456, while the sum is 28.

The square root of 661442131 is about 25718.5172784125. The cubic root of 661442131 is about 871.2924512345.

Adding to 661442131 its reverse (131244166), we get a palindrome (792686297).

The spelling of 661442131 in words is "six hundred sixty-one million, four hundred forty-two thousand, one hundred thirty-one".