231991547681 has 2 divisors, whose sum is σ = 231991547682. Its totient is φ = 231991547680.

The previous prime is 231991547603. The next prime is 231991547701. The reversal of 231991547681 is 186745199132.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 222821761600 + 9169786081 = 472040^2 + 95759^2 .

It is a cyclic number.

It is not a de Polignac number, because 231991547681 - 2²⁶ = 231924438817 is a prime.

It is a super-2 number, since 2×231991547681² (a number of 24 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (231991547881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 115995773840 + 115995773841.

It is an arithmetic number, because the mean of its divisors is an integer number (115995773841).

Almost surely, 2^231991547681 is an apocalyptic number.

It is an amenable number.

231991547681 is a deficient number, since it is larger than the sum of its proper divisors (1).

231991547681 is an equidigital number, since it uses as much as digits as its factorization.

231991547681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3265920, while the sum is 56.

The spelling of 231991547681 in words is "two hundred thirty-one billion, nine hundred ninety-one million, five hundred forty-seven thousand, six hundred eighty-one".