1661563215 has 72 divisors (see below), whose sum is σ = 3191780592. Its totient is φ = 798819840.

The previous prime is 1661563213. The next prime is 1661563247. The reversal of 1661563215 is 5123651661.

1661563215 is a `hidden beast` number, since 1 + 6 + 6 + 1 + 5 + 632 + 15 = 666.

It is not a de Polignac number, because 1661563215 - 2¹ = 1661563213 is a prime.

It is a super-2 number, since 2×1661563215² = 5521584634882272450, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1661563215.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661563213) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 324475 + ... + 329555.

It is an arithmetic number, because the mean of its divisors is an integer number (44330286).

Almost surely, 2^1661563215 is an apocalyptic number.

1661563215 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

1661563215 is a deficient number, since it is larger than the sum of its proper divisors (1530217377).

1661563215 is a wasteful number, since it uses less digits than its factorization.

1661563215 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5161 (or 5145 counting only the distinct ones).

The product of its digits is 32400, while the sum is 36.

The square root of 1661563215 is about 40762.2768623147. The cubic root of 1661563215 is about 1184.4197019861.

The spelling of 1661563215 in words is "one billion, six hundred sixty-one million, five hundred sixty-three thousand, two hundred fifteen".