21251299 has 2 divisors, whose sum is σ = 21251300. Its totient is φ = 21251298.

The previous prime is 21251281. The next prime is 21251311. The reversal of 21251299 is 99215212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21251299 - 2⁵ = 21251267 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21251299.

It is not a weakly prime, because it can be changed into another prime (21251239) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10625649 + 10625650.

It is an arithmetic number, because the mean of its divisors is an integer number (10625650).

Almost surely, 2^21251299 is an apocalyptic number.

21251299 is a deficient number, since it is larger than the sum of its proper divisors (1).

21251299 is an equidigital number, since it uses as much as digits as its factorization.

21251299 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3240, while the sum is 31.

The square root of 21251299 is about 4609.9131228256. The cubic root of 21251299 is about 276.9885566569.

The spelling of 21251299 in words is "twenty-one million, two hundred fifty-one thousand, two hundred ninety-nine".