243640881 has 45 divisors (see below), whose sum is σ = 396327945. Its totient is φ = 144227160.

The previous prime is 243640879. The next prime is 243640949. The reversal of 243640881 is 188046342.

The square root of 243640881 is 15609.

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

243640881 is a `hidden beast` number, since 2 + 4 + 3 + 640 + 8 + 8 + 1 = 666.

It is not a de Polignac number, because 243640881 - 2¹ = 243640879 is a prime.

It is a super-2 number, since 2×243640881² = 118721757788912322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (243640801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 44 ways as a sum of consecutive naturals, for example, 5666046 + ... + 5666088.

Almost surely, 2^243640881 is an apocalyptic number.

243640881 is the 15609-th square number.

243640881 is the 7805-th centered octagonal number.

It is an amenable number.

243640881 is a deficient number, since it is larger than the sum of its proper divisors (152687064).

243640881 is an frugal number, since it uses more digits than its factorization.

243640881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 36.

The cubic root of 243640881 is about 624.5732604824.

Multiplying 243640881 by its sum of digits (36), we get a square (8771071716 = 93654²).

Multiplying 243640881 by its product of nonzero digits (36864), we get a square (8981577437184 = 2996928²).

The spelling of 243640881 in words is "two hundred forty-three million, six hundred forty thousand, eight hundred eighty-one".