3815515661 has 8 divisors (see below), whose sum is σ = 3860418744. Its totient is φ = 3770726400.

The previous prime is 3815515651. The next prime is 3815515699. The reversal of 3815515661 is 1665155183.

It can be written as a sum of positive squares in 4 ways, for example, as 122522761 + 3692992900 = 11069^2 + 60770^2 .

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 3815515661 - 2⁶ = 3815515597 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 (3815515651) 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, 39941 + ... + 96053.

It is an arithmetic number, because the mean of its divisors is an integer number (482552343).

Almost surely, 2^3815515661 is an apocalyptic number.

It is an amenable number.

3815515661 is a deficient number, since it is larger than the sum of its proper divisors (44903083).

3815515661 is an equidigital number, since it uses as much as digits as its factorization.

3815515661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56911.

The product of its digits is 108000, while the sum is 41.

The square root of 3815515661 is about 61769.8604579936. The cubic root of 3815515661 is about 1562.6117302588.

The spelling of 3815515661 in words is "three billion, eight hundred fifteen million, five hundred fifteen thousand, six hundred sixty-one".