261215982 has 128 divisors (see below), whose sum is σ = 648622080. Its totient is φ = 77552640.

The previous prime is 261215921. The next prime is 261216001. The reversal of 261215982 is 289512162.

261215982 is a `hidden beast` number, since 2 + 61 + 2 + 1 + 598 + 2 = 666.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1906618 + ... + 1906754.

It is an arithmetic number, because the mean of its divisors is an integer number (5067360).

Almost surely, 2^261215982 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261215982, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (324311040).

261215982 is an abundant number, since it is smaller than the sum of its proper divisors (387406098).

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

261215982 is a wasteful number, since it uses less digits than its factorization.

261215982 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 263 (or 257 counting only the distinct ones).

The product of its digits is 17280, while the sum is 36.

The square root of 261215982 is about 16162.1775141842. The cubic root of 261215982 is about 639.2438840711.

The spelling of 261215982 in words is "two hundred sixty-one million, two hundred fifteen thousand, nine hundred eighty-two".