21124331 has 4 divisors (see below), whose sum is σ = 21250992. Its totient is φ = 20997672.

The previous prime is 21124321. The next prime is 21124339. The reversal of 21124331 is 13342112.

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

It is a cyclic number.

It is not a de Polignac number, because 21124331 - 2¹⁸ = 20862187 is a prime.

It is a super-2 number, since 2×21124331² = 892474720395122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21124339) 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, 63080 + ... + 63413.

It is an arithmetic number, because the mean of its divisors is an integer number (5312748).

Almost surely, 2^21124331 is an apocalyptic number.

21124331 is a deficient number, since it is larger than the sum of its proper divisors (126661).

21124331 is a wasteful number, since it uses less digits than its factorization.

21124331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126660.

The product of its digits is 144, while the sum is 17.

The square root of 21124331 is about 4596.1212995307. The cubic root of 21124331 is about 276.4358225069.

Adding to 21124331 its reverse (13342112), we get a palindrome (34466443).

It can be divided in two parts, 211 and 24331, that added together give a palindrome (24542).

The spelling of 21124331 in words is "twenty-one million, one hundred twenty-four thousand, three hundred thirty-one".