18757561 has 9 divisors (see below), whose sum is σ = 19342479. Its totient is φ = 18190200.

The previous prime is 18757553. The next prime is 18757591. The reversal of 18757561 is 16575781.

The square root of 18757561 is 4331.

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

It can be written as a sum of positive squares in only one way, i.e., 609961 + 18147600 = 781^2 + 4260^2 .

It is not a de Polignac number, because 18757561 - 2³ = 18757553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18757591) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 264156 + ... + 264226.

Almost surely, 2^18757561 is an apocalyptic number.

18757561 is the 4331-st square number.

18757561 is the 2166-th centered octagonal number.

It is an amenable number.

18757561 is a deficient number, since it is larger than the sum of its proper divisors (584918).

18757561 is an frugal number, since it uses more digits than its factorization.

18757561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 264 (or 132 counting only the distinct ones).

The product of its digits is 58800, while the sum is 40.

The cubic root of 18757561 is about 265.7003475475.

The spelling of 18757561 in words is "eighteen million, seven hundred fifty-seven thousand, five hundred sixty-one".