231978787 has 4 divisors (see below), whose sum is σ = 245624616. Its totient is φ = 218332960.

The previous prime is 231978781. The next prime is 231978823. The reversal of 231978787 is 787879132.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 231978787 - 2¹¹ = 231976739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231978781) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6822889 + ... + 6822922.

It is an arithmetic number, because the mean of its divisors is an integer number (61406154).

Almost surely, 2^231978787 is an apocalyptic number.

231978787 is a deficient number, since it is larger than the sum of its proper divisors (13645829).

231978787 is a wasteful number, since it uses less digits than its factorization.

231978787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13645828.

The product of its digits is 1185408, while the sum is 52.

The square root of 231978787 is about 15230.8498449693. The cubic root of 231978787 is about 614.4446366765. Note that the first 3 decimals are identical.

The spelling of 231978787 in words is "two hundred thirty-one million, nine hundred seventy-eight thousand, seven hundred eighty-seven".