1661516615 has 16 divisors (see below), whose sum is σ = 2175970176. Its totient is φ = 1207879200.

The previous prime is 1661516611. The next prime is 1661516621. The reversal of 1661516615 is 5166151661.

It is not a de Polignac number, because 1661516615 - 2² = 1661516611 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661516611) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 178220 + ... + 187310.

It is an arithmetic number, because the mean of its divisors is an integer number (135998136).

Almost surely, 2^1661516615 is an apocalyptic number.

1661516615 is a deficient number, since it is larger than the sum of its proper divisors (514453561).

1661516615 is a wasteful number, since it uses less digits than its factorization.

1661516615 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12430.

The product of its digits is 32400, while the sum is 38.

The square root of 1661516615 is about 40761.7052513753. The cubic root of 1661516615 is about 1184.4086291855.

The spelling of 1661516615 in words is "one billion, six hundred sixty-one million, five hundred sixteen thousand, six hundred fifteen".