661539774 has 16 divisors (see below), whose sum is σ = 1512091008. Its totient is φ = 189011352.

The previous prime is 661539773. The next prime is 661539779. The reversal of 661539774 is 477935166.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661539773) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 7875432 + ... + 7875515.

It is an arithmetic number, because the mean of its divisors is an integer number (94505688).

Almost surely, 2^661539774 is an apocalyptic number.

661539774 is an abundant number, since it is smaller than the sum of its proper divisors (850551234).

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

661539774 is a wasteful number, since it uses less digits than its factorization.

661539774 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15750959.

The product of its digits is 952560, while the sum is 48.

The square root of 661539774 is about 25720.4155098630. The cubic root of 661539774 is about 871.3353229229.

The spelling of 661539774 in words is "six hundred sixty-one million, five hundred thirty-nine thousand, seven hundred seventy-four".