661144815 has 24 divisors (see below), whose sum is σ = 1175899920. Its totient is φ = 352451232.

The previous prime is 661144787. The next prime is 661144837. The reversal of 661144815 is 518441166.

661144815 is a `hidden beast` number, since 66 + 114 + 481 + 5 = 666.

It is not a de Polignac number, because 661144815 - 2⁶ = 661144751 is a prime.

It is a super-2 number, since 2×661144815² = 874224932802768450, 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 661144815.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 297649 + ... + 299861.

It is an arithmetic number, because the mean of its divisors is an integer number (48995830).

Almost surely, 2^661144815 is an apocalyptic number.

661144815 is a deficient number, since it is larger than the sum of its proper divisors (514755105).

661144815 is an frugal number, since it uses more digits than its factorization.

661144815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4440 (or 2221 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 661144815 is about 25712.7364354710. The cubic root of 661144815 is about 871.1618839997.

The spelling of 661144815 in words is "six hundred sixty-one million, one hundred forty-four thousand, eight hundred fifteen".