21243151 has 2 divisors, whose sum is σ = 21243152. Its totient is φ = 21243150.

The previous prime is 21243139. The next prime is 21243181. The reversal of 21243151 is 15134212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21243151 - 2⁷ = 21243023 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243181) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10621575 + 10621576.

It is an arithmetic number, because the mean of its divisors is an integer number (10621576).

Almost surely, 2^21243151 is an apocalyptic number.

21243151 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243151 is an equidigital number, since it uses as much as digits as its factorization.

21243151 is an evil number, because the sum of its binary digits is even.

The product of its digits is 240, while the sum is 19.

The square root of 21243151 is about 4609.0292904255. The cubic root of 21243151 is about 276.9531518994.

Adding to 21243151 its reverse (15134212), we get a palindrome (36377363).

The spelling of 21243151 in words is "twenty-one million, two hundred forty-three thousand, one hundred fifty-one".