21101231 has 4 divisors (see below), whose sum is σ = 21243000. Its totient is φ = 20959464.

The previous prime is 21101219. The next prime is 21101243. The reversal of 21101231 is 13210112.

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

It is an interprime number because it is at equal distance from previous prime (21101219) and next prime (21101243).

It is a cyclic number.

It is not a de Polignac number, because 21101231 - 2¹⁰ = 21100207 is a prime.

It is a super-2 number, since 2×21101231² = 890523899430722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70661 + ... + 70958.

It is an arithmetic number, because the mean of its divisors is an integer number (5310750).

Almost surely, 2^21101231 is an apocalyptic number.

21101231 is a deficient number, since it is larger than the sum of its proper divisors (141769).

21101231 is a wasteful number, since it uses less digits than its factorization.

21101231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 141768.

The product of its (nonzero) digits is 12, while the sum is 11.

The square root of 21101231 is about 4593.6076236440. The cubic root of 21101231 is about 276.3350225250.

Adding to 21101231 its reverse (13210112), we get a palindrome (34311343).

The spelling of 21101231 in words is "twenty-one million, one hundred one thousand, two hundred thirty-one".