661877745 has 64 divisors (see below), whose sum is σ = 1170339840. Its totient is φ = 317952000.

The previous prime is 661877681. The next prime is 661877761. The reversal of 661877745 is 547778166.

It is not a de Polignac number, because 661877745 - 2⁶ = 661877681 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (51).

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 797991 + ... + 798819.

It is an arithmetic number, because the mean of its divisors is an integer number (18286560).

Almost surely, 2^661877745 is an apocalyptic number.

It is an amenable number.

661877745 is a deficient number, since it is larger than the sum of its proper divisors (508462095).

661877745 is a wasteful number, since it uses less digits than its factorization.

661877745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 986.

The product of its digits is 1975680, while the sum is 51.

The square root of 661877745 is about 25726.9847630848. The cubic root of 661877745 is about 871.4836818207.

The spelling of 661877745 in words is "six hundred sixty-one million, eight hundred seventy-seven thousand, seven hundred forty-five".