1261896491 has 4 divisors (see below), whose sum is σ = 1266452352. Its totient is φ = 1257340632.

The previous prime is 1261896463. The next prime is 1261896499. The reversal of 1261896491 is 1946981621.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1946981621 = 13 ⋅149767817.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1261896491 is a prime.

It is a super-2 number, since 2×1261896491² = 3184765507996226162, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1261896499) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2277515 + ... + 2278068.

It is an arithmetic number, because the mean of its divisors is an integer number (316613088).

Almost surely, 2^1261896491 is an apocalyptic number.

1261896491 is a deficient number, since it is larger than the sum of its proper divisors (4555861).

1261896491 is an equidigital number, since it uses as much as digits as its factorization.

1261896491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4555860.

The product of its digits is 186624, while the sum is 47.

The square root of 1261896491 is about 35523.1824447079. The cubic root of 1261896491 is about 1080.6239224658.

The spelling of 1261896491 in words is "one billion, two hundred sixty-one million, eight hundred ninety-six thousand, four hundred ninety-one".