21453331 has 2 divisors, whose sum is σ = 21453332. Its totient is φ = 21453330.

The previous prime is 21453323. The next prime is 21453347. The reversal of 21453331 is 13335412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21453331 - 2³ = 21453323 is a prime.

It is a super-2 number, since 2×21453331² = 920490821991122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21453391) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10726665 + 10726666.

It is an arithmetic number, because the mean of its divisors is an integer number (10726666).

Almost surely, 2^21453331 is an apocalyptic number.

21453331 is a deficient number, since it is larger than the sum of its proper divisors (1).

21453331 is an equidigital number, since it uses as much as digits as its factorization.

21453331 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1080, while the sum is 22.

The square root of 21453331 is about 4631.7740661651. The cubic root of 21453331 is about 277.8635486186.

Adding to 21453331 its reverse (13335412), we get a palindrome (34788743).

It can be divided in two parts, 2145 and 3331, that added together give a square (5476 = 74²).

The spelling of 21453331 in words is "twenty-one million, four hundred fifty-three thousand, three hundred thirty-one".