661877145 has 48 divisors (see below), whose sum is σ = 1194704784. Its totient is φ = 338688000.

The previous prime is 661877131. The next prime is 661877149. The reversal of 661877145 is 541778166.

It can be written as a sum of positive squares in 8 ways, for example, as 137100681 + 524776464 = 11709^2 + 22908^2 .

It is not a de Polignac number, because 661877145 - 2⁴ = 661877129 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 661877145.

It is not an unprimeable number, because it can be changed into a prime (661877149) 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 47 ways as a sum of consecutive naturals, for example, 109605 + ... + 115485.

It is an arithmetic number, because the mean of its divisors is an integer number (24889683).

It is the magic constant of a 1098 × 1098 magic square.

Almost surely, 2^661877145 is an apocalyptic number.

It is an amenable number.

661877145 is a deficient number, since it is larger than the sum of its proper divisors (532827639).

661877145 is a wasteful number, since it uses less digits than its factorization.

661877145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5994 (or 5991 counting only the distinct ones).

The product of its digits is 282240, while the sum is 45.

The square root of 661877145 is about 25726.9731021743. The cubic root of 661877145 is about 871.4834184839.

The spelling of 661877145 in words is "six hundred sixty-one million, eight hundred seventy-seven thousand, one hundred forty-five".