21231331 has 8 divisors (see below), whose sum is σ = 23214528. Its totient is φ = 19257000.

The previous prime is 21231313. The next prime is 21231359. The reversal of 21231331 is 13313212.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21231331 - 2²¹ = 19134179 is a prime.

It is a super-2 number, since 2×21231331² = 901538832063122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21231391) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3436 + ... + 7366.

It is an arithmetic number, because the mean of its divisors is an integer number (2901816).

Almost surely, 2^21231331 is an apocalyptic number.

21231331 is a deficient number, since it is larger than the sum of its proper divisors (1983197).

21231331 is a wasteful number, since it uses less digits than its factorization.

21231331 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4433.

The product of its digits is 108, while the sum is 16.

The square root of 21231331 is about 4607.7468463448. The cubic root of 21231331 is about 276.9017754409.

Adding to 21231331 its reverse (13313212), we get a palindrome (34544543).

The spelling of 21231331 in words is "twenty-one million, two hundred thirty-one thousand, three hundred thirty-one".