661531512 has 32 divisors (see below), whose sum is σ = 1740873600. Its totient is φ = 208904544.

The previous prime is 661531511. The next prime is 661531579. The reversal of 661531512 is 215135166.

It is a super-2 number, since 2×661531512² = 875247882738012288, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 661531512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661531511) 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 7 ways as a sum of consecutive naturals, for example, 724908 + ... + 725819.

It is an arithmetic number, because the mean of its divisors is an integer number (54402300).

Almost surely, 2^661531512 is an apocalyptic number.

It is an amenable number.

661531512 is an abundant number, since it is smaller than the sum of its proper divisors (1079342088).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

661531512 is a wasteful number, since it uses less digits than its factorization.

661531512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1450755 (or 1450751 counting only the distinct ones).

The product of its digits is 5400, while the sum is 30.

The square root of 661531512 is about 25720.2548976483. The cubic root of 661531512 is about 871.3316955258.

Adding to 661531512 its reverse (215135166), we get a palindrome (876666678).

The spelling of 661531512 in words is "six hundred sixty-one million, five hundred thirty-one thousand, five hundred twelve".