261540245 has 24 divisors (see below), whose sum is σ = 333671352. Its totient is φ = 196732800.

The previous prime is 261540217. The next prime is 261540259. The reversal of 261540245 is 542045162.

It can be written as a sum of positive squares in 4 ways, for example, as 6754801 + 254785444 = 2599^2 + 15962^2 .

It is not a de Polignac number, because 261540245 - 2¹⁶ = 261474709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 160535 + ... + 162155.

It is an arithmetic number, because the mean of its divisors is an integer number (13902973).

Almost surely, 2^261540245 is an apocalyptic number.

It is an amenable number.

261540245 is a deficient number, since it is larger than the sum of its proper divisors (72131107).

261540245 is a wasteful number, since it uses less digits than its factorization.

261540245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1733 (or 1710 counting only the distinct ones).

The product of its (nonzero) digits is 9600, while the sum is 29.

The square root of 261540245 is about 16172.2059410583. The cubic root of 261540245 is about 639.5082852333.

The spelling of 261540245 in words is "two hundred sixty-one million, five hundred forty thousand, two hundred forty-five".