21000000231 has 24 divisors (see below), whose sum is σ = 35862072480. Its totient is φ = 11586206016.

The previous prime is 21000000209. The next prime is 21000000271. The reversal of 21000000231 is 13200000012.

It is a happy number.

It is not a de Polignac number, because 21000000231 - 2⁶ = 21000000167 is a prime.

It is a super-2 number, since 2×21000000231² (a number of 21 digits) contains 22 as substring.

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

21000000231 is a modest number, since divided by 231 gives 210 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21000000271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 5745300 + ... + 5748953.

It is an arithmetic number, because the mean of its divisors is an integer number (1494253020).

Almost surely, 2^21000000231 is an apocalyptic number.

21000000231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21000000231 is a deficient number, since it is larger than the sum of its proper divisors (14862072249).

21000000231 is a wasteful number, since it uses less digits than its factorization.

21000000231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11494295 (or 11494292 counting only the distinct ones).

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

Adding to 21000000231 its reverse (13200000012), we get a palindrome (34200000243).

The spelling of 21000000231 in words is "twenty-one billion, two hundred thirty-one", and thus it is an aban number.