231000021 has 24 divisors (see below), whose sum is σ = 381879680. Its totient is φ = 131810976.

The previous prime is 231000013. The next prime is 231000041. The reversal of 231000021 is 120000132.

It is a happy number.

It is not a de Polignac number, because 231000021 - 2³ = 231000013 is a prime.

It is a super-2 number, since 2×231000021² = 106722019404000882, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 230999967 and 231000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231000041) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 50016 + ... + 54438.

Almost surely, 2^231000021 is an apocalyptic number.

231000021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

231000021 is a deficient number, since it is larger than the sum of its proper divisors (150879659).

231000021 is a wasteful number, since it uses less digits than its factorization.

231000021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5265 (or 5262 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 231000021 is about 15198.6848444199. The cubic root of 231000021 is about 613.5792625595.

Adding to 231000021 its reverse (120000132), we get a palindrome (351000153).

The spelling of 231000021 in words is "two hundred thirty-one million, twenty-one", and thus it is an aban number.