21121331 has 16 divisors (see below), whose sum is σ = 27720960. Its totient is φ = 15590880.

The previous prime is 21121319. The next prime is 21121333. The reversal of 21121331 is 13312112.

It is a cyclic number.

It is not a de Polignac number, because 21121331 - 2¹⁴ = 21104947 is a prime.

It is a super-2 number, since 2×21121331² = 892221246423122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21121333) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5756 + ... + 8681.

It is an arithmetic number, because the mean of its divisors is an integer number (1732560).

Almost surely, 2^21121331 is an apocalyptic number.

21121331 is a deficient number, since it is larger than the sum of its proper divisors (6599629).

21121331 is a wasteful number, since it uses less digits than its factorization.

21121331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14474.

The product of its digits is 36, while the sum is 14.

The square root of 21121331 is about 4595.7949257990. The cubic root of 21121331 is about 276.4227357535.

Adding to 21121331 its reverse (13312112), we get a palindrome (34433443).

It can be divided in two parts, 2112 and 1331, that added together give a palindrome (3443).

The spelling of 21121331 in words is "twenty-one million, one hundred twenty-one thousand, three hundred thirty-one".