661158369 has 15 divisors (see below), whose sum is σ = 988002147. Its totient is φ = 440617968.

The previous prime is 661158331. The next prime is 661158383. The reversal of 661158369 is 963851166.

The square root of 661158369 is 25713.

It is a perfect power (a square), and thus also a powerful number.

661158369 is a `hidden beast` number, since 6 + 6 + 1 + 1 + 583 + 69 = 666.

It can be written as a sum of positive squares in only one way, i.e., 445421025 + 215737344 = 21105^2 + 14688^2 .

It is not a de Polignac number, because 661158369 - 2⁷ = 661158241 is a prime.

It is a super-2 number, since 2×661158369² = 874260777797480322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (661158569) by changing a digit.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 229989 + ... + 232845.

Almost surely, 2^661158369 is an apocalyptic number.

661158369 is the 25713-rd square number.

661158369 is the 12857-th centered octagonal number.

It is an amenable number.

661158369 is a deficient number, since it is larger than the sum of its proper divisors (326843778).

661158369 is an frugal number, since it uses more digits than its factorization.

661158369 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5726 (or 2860 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The cubic root of 661158369 is about 871.1678371320.

It can be divided in two parts, 6611 and 58369, that added together give a triangular number (64980 = T₃₆₀).

The spelling of 661158369 in words is "six hundred sixty-one million, one hundred fifty-eight thousand, three hundred sixty-nine".