231211987 has 4 divisors (see below), whose sum is σ = 232977096. Its totient is φ = 229446880.

The previous prime is 231211961. The next prime is 231212057. The reversal of 231211987 is 789112132.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-231211987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (231211957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 882358 + ... + 882619.

It is an arithmetic number, because the mean of its divisors is an integer number (58244274).

Almost surely, 2^231211987 is an apocalyptic number.

231211987 is a deficient number, since it is larger than the sum of its proper divisors (1765109).

231211987 is a wasteful number, since it uses less digits than its factorization.

231211987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1765108.

The product of its digits is 6048, while the sum is 34.

The square root of 231211987 is about 15205.6564146373. The cubic root of 231211987 is about 613.7668789664.

The spelling of 231211987 in words is "two hundred thirty-one million, two hundred eleven thousand, nine hundred eighty-seven".