1231726981 has 16 divisors (see below), whose sum is σ = 1303102080. Its totient is φ = 1161909760.

The previous prime is 1231726933. The next prime is 1231727023. The reversal of 1231726981 is 1896271321.

It is a cyclic number.

It is not a de Polignac number, because 1231726981 - 2¹⁷ = 1231595909 is a prime.

It is a super-2 number, since 2×1231726981² = 3034302711446748722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1231726921) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1397661 + ... + 1398541.

It is an arithmetic number, because the mean of its divisors is an integer number (81443880).

It is a Poulet number, since it divides 2^1231726980-1.

Almost surely, 2^1231726981 is an apocalyptic number.

1231726981 is the 20263-rd octagonal number.

It is an amenable number.

1231726981 is a deficient number, since it is larger than the sum of its proper divisors (71375099).

1231726981 is an equidigital number, since it uses as much as digits as its factorization.

1231726981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1676.

The product of its digits is 36288, while the sum is 40.

The square root of 1231726981 is about 35095.9681587501. The cubic root of 1231726981 is about 1071.9424874121.

The spelling of 1231726981 in words is "one billion, two hundred thirty-one million, seven hundred twenty-six thousand, nine hundred eighty-one".