261987558 has 32 divisors (see below), whose sum is σ = 608651520. Its totient is φ = 73625760.

The previous prime is 261987547. The next prime is 261987569. The reversal of 261987558 is 855789162.

It is an interprime number because it is at equal distance from previous prime (261987547) and next prime (261987569).

It is a self number, because there is not a number n which added to its sum of digits gives 261987558.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48568 + ... + 53691.

It is an arithmetic number, because the mean of its divisors is an integer number (19020360).

Almost surely, 2^261987558 is an apocalyptic number.

261987558 is an abundant number, since it is smaller than the sum of its proper divisors (346663962).

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

261987558 is a wasteful number, since it uses less digits than its factorization.

261987558 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102332.

The product of its digits is 1209600, while the sum is 51.

The square root of 261987558 is about 16186.0297170121. The cubic root of 261987558 is about 639.8726618402.

The spelling of 261987558 in words is "two hundred sixty-one million, nine hundred eighty-seven thousand, five hundred fifty-eight".