231501533661 has 6 divisors (see below), whose sum is σ = 334391104190. Its totient is φ = 154334355768.

The previous prime is 231501533647. The next prime is 231501533677. The reversal of 231501533661 is 166335105132.

231501533661 is a `hidden beast` number, since 2 + 315 + 0 + 1 + 5 + 336 + 6 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 230788964025 + 712569636 = 480405^2 + 26694^2 .

It is not a de Polignac number, because 231501533661 - 2⁷ = 231501533533 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231501583661) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12861196306 + ... + 12861196323.

Almost surely, 2^231501533661 is an apocalyptic number.

It is an amenable number.

231501533661 is a deficient number, since it is larger than the sum of its proper divisors (102889570529).

231501533661 is a wasteful number, since it uses less digits than its factorization.

231501533661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25722392635 (or 25722392632 counting only the distinct ones).

The product of its (nonzero) digits is 48600, while the sum is 36.

Adding to 231501533661 its reverse (166335105132), we get a palindrome (397836638793).

The spelling of 231501533661 in words is "two hundred thirty-one billion, five hundred one million, five hundred thirty-three thousand, six hundred sixty-one".