1665659380 has 72 divisors (see below), whose sum is σ = 4394081664. Its totient is φ = 519161280.

The previous prime is 1665659363. The next prime is 1665659381. The reversal of 1665659380 is 839565661.

It is a happy number.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665659381) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 32224 + ... + 66103.

It is an arithmetic number, because the mean of its divisors is an integer number (61028912).

Almost surely, 2^1665659380 is an apocalyptic number.

1665659380 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1665659380 is an abundant number, since it is smaller than the sum of its proper divisors (2728422284).

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

1665659380 is a wasteful number, since it uses less digits than its factorization.

1665659380 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98365 (or 98352 counting only the distinct ones).

The product of its (nonzero) digits is 1166400, while the sum is 49.

The square root of 1665659380 is about 40812.4904900448. The cubic root of 1665659380 is about 1185.3921992816.

The spelling of 1665659380 in words is "one billion, six hundred sixty-five million, six hundred fifty-nine thousand, three hundred eighty".