1261689831 has 8 divisors (see below), whose sum is σ = 1869170160. Its totient is φ = 841126536.

The previous prime is 1261689811. The next prime is 1261689839. The reversal of 1261689831 is 1389861621.

It is not a de Polignac number, because 1261689831 - 2¹⁰ = 1261688807 is a prime.

It is a super-2 number, since 2×1261689831² = 3183722459297617122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1261689839) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23364600 + ... + 23364653.

It is an arithmetic number, because the mean of its divisors is an integer number (233646270).

Almost surely, 2^1261689831 is an apocalyptic number.

1261689831 is a deficient number, since it is larger than the sum of its proper divisors (607480329).

1261689831 is an equidigital number, since it uses as much as digits as its factorization.

1261689831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46729262 (or 46729256 counting only the distinct ones).

The product of its digits is 124416, while the sum is 45.

The square root of 1261689831 is about 35520.2735209063. The cubic root of 1261689831 is about 1080.5649282103.

The spelling of 1261689831 in words is "one billion, two hundred sixty-one million, six hundred eighty-nine thousand, eight hundred thirty-one".