1261861587 has 48 divisors (see below), whose sum is σ = 2107123200. Its totient is φ = 712800000.

The previous prime is 1261861547. The next prime is 1261861597. The reversal of 1261861587 is 7851681621.

1261861587 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 8 + 61 + 587 = 666.

It is not a de Polignac number, because 1261861587 - 2²² = 1257667283 is a prime.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1261861547) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3146587 + ... + 3146987.

It is an arithmetic number, because the mean of its divisors is an integer number (43898400).

Almost surely, 2^1261861587 is an apocalyptic number.

1261861587 is a deficient number, since it is larger than the sum of its proper divisors (845261613).

1261861587 is a wasteful number, since it uses less digits than its factorization.

1261861587 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864 (or 861 counting only the distinct ones).

The product of its digits is 161280, while the sum is 45.

The square root of 1261861587 is about 35522.6911564988. The cubic root of 1261861587 is about 1080.6139590376.

The spelling of 1261861587 in words is "one billion, two hundred sixty-one million, eight hundred sixty-one thousand, five hundred eighty-seven".