243654561 has 20 divisors (see below), whose sum is σ = 364438932. Its totient is φ = 162230688.

The previous prime is 243654553. The next prime is 243654569. The reversal of 243654561 is 165456342.

243654561 is a `hidden beast` number, since 2 + 43 + 6 + 54 + 561 = 666.

It is an interprime number because it is at equal distance from previous prime (243654553) and next prime (243654569).

It can be written as a sum of positive squares in 2 ways, for example, as 46785600 + 196868961 = 6840^2 + 14031^2 .

It is not a de Polignac number, because 243654561 - 2³ = 243654553 is a prime.

It is a super-2 number, since 2×243654561² = 118735090192205442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243654569) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 89131 + ... + 91823.

Almost surely, 2^243654561 is an apocalyptic number.

It is an amenable number.

243654561 is a deficient number, since it is larger than the sum of its proper divisors (120784371).

243654561 is a wasteful number, since it uses less digits than its factorization.

243654561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3822 (or 3813 counting only the distinct ones).

The product of its digits is 86400, while the sum is 36.

The square root of 243654561 is about 15609.4382025747. The cubic root of 243654561 is about 624.5849498210.

The spelling of 243654561 in words is "two hundred forty-three million, six hundred fifty-four thousand, five hundred sixty-one".