21142331 has 4 divisors (see below), whose sum is σ = 24162672. Its totient is φ = 18121992.

The previous prime is 21142291. The next prime is 21142343. The reversal of 21142331 is 13324112.

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

It is not a de Polignac number, because 21142331 - 2¹⁸ = 20880187 is a prime.

It is a super-2 number, since 2×21142331² = 893996320227122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21142351) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1510160 + ... + 1510173.

It is an arithmetic number, because the mean of its divisors is an integer number (6040668).

Almost surely, 2^21142331 is an apocalyptic number.

21142331 is a deficient number, since it is larger than the sum of its proper divisors (3020341).

21142331 is an equidigital number, since it uses as much as digits as its factorization.

21142331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3020340.

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

The square root of 21142331 is about 4598.0790554317. The cubic root of 21142331 is about 276.5143170191.

Adding to 21142331 its reverse (13324112), we get a palindrome (34466443).

The spelling of 21142331 in words is "twenty-one million, one hundred forty-two thousand, three hundred thirty-one".