21100231 has 2 divisors, whose sum is σ = 21100232. Its totient is φ = 21100230.

The previous prime is 21100217. The next prime is 21100253. The reversal of 21100231 is 13200112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21100231 - 2⁷ = 21100103 is a prime.

It is a super-2 number, since 2×21100231² = 890439496506722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21100531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10550115 + 10550116.

It is an arithmetic number, because the mean of its divisors is an integer number (10550116).

Almost surely, 2^21100231 is an apocalyptic number.

21100231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21100231 is an equidigital number, since it uses as much as digits as its factorization.

21100231 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21100231 is about 4593.4987754434. The cubic root of 21100231 is about 276.3306572286.

Adding to 21100231 its reverse (13200112), we get a palindrome (34300343).

The spelling of 21100231 in words is "twenty-one million, one hundred thousand, two hundred thirty-one".