1661239819 has 8 divisors (see below), whose sum is σ = 1678664592. Its totient is φ = 1643834400.

The previous prime is 1661239807. The next prime is 1661239829. The reversal of 1661239819 is 9189321661.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 1661239819 - 2⁷ = 1661239691 is a prime.

It is a super-2 number, since 2×1661239819² = 5519435472462305522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1661239829) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 222877 + ... + 230209.

It is an arithmetic number, because the mean of its divisors is an integer number (209833074).

Almost surely, 2^1661239819 is an apocalyptic number.

1661239819 is a deficient number, since it is larger than the sum of its proper divisors (17424773).

1661239819 is a wasteful number, since it uses less digits than its factorization.

1661239819 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9677.

The product of its digits is 139968, while the sum is 46.

The square root of 1661239819 is about 40758.3098153002. The cubic root of 1661239819 is about 1184.3428543838.

The spelling of 1661239819 in words is "one billion, six hundred sixty-one million, two hundred thirty-nine thousand, eight hundred nineteen".