261321570 has 48 divisors (see below), whose sum is σ = 681919992. Its totient is φ = 69431040.

The previous prime is 261321559. The next prime is 261321587. The reversal of 261321570 is 75123162.

It is a happy number.

261321570 is a `hidden beast` number, since 2 + 61 + 32 + 1 + 570 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 245329569 + 15992001 = 15663^2 + 3999^2 .

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, 20124 + ... + 30456.

Almost surely, 2^261321570 is an apocalyptic number.

261321570 is an abundant number, since it is smaller than the sum of its proper divisors (420598422).

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

261321570 is a wasteful number, since it uses less digits than its factorization.

261321570 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10627 (or 10624 counting only the distinct ones).

The product of its (nonzero) digits is 2520, while the sum is 27.

The square root of 261321570 is about 16165.4436994473. The cubic root of 261321570 is about 639.3300035986.

The spelling of 261321570 in words is "two hundred sixty-one million, three hundred twenty-one thousand, five hundred seventy".