261393564 has 72 divisors (see below), whose sum is σ = 682178560. Its totient is φ = 77670144.

The previous prime is 261393557. The next prime is 261393571. The reversal of 261393564 is 465393162.

261393564 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (261393557) and next prime (261393571).

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, 63909 + ... + 67875.

Almost surely, 2^261393564 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261393564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (341089280).

261393564 is an abundant number, since it is smaller than the sum of its proper divisors (420784996).

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

261393564 is a wasteful number, since it uses less digits than its factorization.

261393564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4027 (or 4008 counting only the distinct ones).

The product of its digits is 116640, while the sum is 39.

The square root of 261393564 is about 16167.6703331061. The cubic root of 261393564 is about 639.3887099377.

The spelling of 261393564 in words is "two hundred sixty-one million, three hundred ninety-three thousand, five hundred sixty-four".