1261257558 has 16 divisors (see below), whose sum is σ = 2751834816. Its totient is φ = 382199240.

The previous prime is 1261257527. The next prime is 1261257581. The reversal of 1261257558 is 8557521621.

It is a super-2 number, since 2×1261257558² = 3181541255224246728, which contains 22 as substring.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 9554916 + ... + 9555047.

It is an arithmetic number, because the mean of its divisors is an integer number (171989676).

Almost surely, 2^1261257558 is an apocalyptic number.

1261257558 is an abundant number, since it is smaller than the sum of its proper divisors (1490577258).

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

1261257558 is a wasteful number, since it uses less digits than its factorization.

1261257558 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19109979.

The product of its digits is 168000, while the sum is 42.

The square root of 1261257558 is about 35514.1881224955. The cubic root of 1261257558 is about 1080.4415084424.

The spelling of 1261257558 in words is "one billion, two hundred sixty-one million, two hundred fifty-seven thousand, five hundred fifty-eight".