261045640 has 16 divisors (see below), whose sum is σ = 587352780. Its totient is φ = 104418240.

The previous prime is 261045623. The next prime is 261045667. The reversal of 261045640 is 46540162.

It can be written as a sum of positive squares in 2 ways, for example, as 258630724 + 2414916 = 16082^2 + 1554^2 .

It is a junction number, because it is equal to n+sod(n) for n = 261045599 and 261045608.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3263031 + ... + 3263110.

Almost surely, 2^261045640 is an apocalyptic number.

261045640 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261045640 is an abundant number, since it is smaller than the sum of its proper divisors (326307140).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261045640 is a wasteful number, since it uses less digits than its factorization.

261045640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6526152 (or 6526148 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 28.

The square root of 261045640 is about 16156.9068821975. The cubic root of 261045640 is about 639.1049010490.

The spelling of 261045640 in words is "two hundred sixty-one million, forty-five thousand, six hundred forty".