21153361 has 2 divisors, whose sum is σ = 21153362. Its totient is φ = 21153360.

The previous prime is 21153359. The next prime is 21153367. The reversal of 21153361 is 16335112.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19749136 + 1404225 = 4444^2 + 1185^2 .

It is a cyclic number.

It is not a de Polignac number, because 21153361 - 2¹ = 21153359 is a prime.

Together with 21153359, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21153367) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10576680 + 10576681.

It is an arithmetic number, because the mean of its divisors is an integer number (10576681).

Almost surely, 2^21153361 is an apocalyptic number.

It is an amenable number.

21153361 is a deficient number, since it is larger than the sum of its proper divisors (1).

21153361 is an equidigital number, since it uses as much as digits as its factorization.

21153361 is an evil number, because the sum of its binary digits is even.

The product of its digits is 540, while the sum is 22.

The square root of 21153361 is about 4599.2783129530. The cubic root of 21153361 is about 276.5623946992.

Adding to 21153361 its reverse (16335112), we get a palindrome (37488473).

It can be divided in two parts, 2115 and 3361, that added together give a square (5476 = 74²).

The spelling of 21153361 in words is "twenty-one million, one hundred fifty-three thousand, three hundred sixty-one".