1661889999 has 32 divisors (see below), whose sum is σ = 2765076480. Its totient is φ = 862552800.

The previous prime is 1661889991. The next prime is 1661890033. The reversal of 1661889999 is 9999881661.

It is not a de Polignac number, because 1661889999 - 2³ = 1661889991 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661889991) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 334564 + ... + 339494.

It is an arithmetic number, because the mean of its divisors is an integer number (86408640).

Almost surely, 2^1661889999 is an apocalyptic number.

1661889999 is a deficient number, since it is larger than the sum of its proper divisors (1103186481).

1661889999 is a wasteful number, since it uses less digits than its factorization.

1661889999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6411.

The product of its digits is 15116544, while the sum is 66.

The square root of 1661889999 is about 40766.2850772547. The cubic root of 1661889999 is about 1184.4973445404.

The spelling of 1661889999 in words is "one billion, six hundred sixty-one million, eight hundred eighty-nine thousand, nine hundred ninety-nine".