21291449 has 2 divisors, whose sum is σ = 21291450. Its totient is φ = 21291448.

The previous prime is 21291437. The next prime is 21291467. The reversal of 21291449 is 94419212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17935225 + 3356224 = 4235^2 + 1832^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21291449 is a prime.

It is not a weakly prime, because it can be changed into another prime (21291499) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10645724 + 10645725.

It is an arithmetic number, because the mean of its divisors is an integer number (10645725).

Almost surely, 2^21291449 is an apocalyptic number.

It is an amenable number.

21291449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21291449 is an equidigital number, since it uses as much as digits as its factorization.

21291449 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5184, while the sum is 32.

The square root of 21291449 is about 4614.2658137563. The cubic root of 21291449 is about 277.1628847331.

The spelling of 21291449 in words is "twenty-one million, two hundred ninety-one thousand, four hundred forty-nine".