21457199 has 2 divisors, whose sum is σ = 21457200. Its totient is φ = 21457198.

The previous prime is 21457193. The next prime is 21457201. The reversal of 21457199 is 99175412.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21457199 is a prime.

It is a super-2 number, since 2×21457199² = 920822777851202, which contains 22 as substring.

Together with 21457201, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21457193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10728599 + 10728600.

It is an arithmetic number, because the mean of its divisors is an integer number (10728600).

Almost surely, 2^21457199 is an apocalyptic number.

21457199 is a deficient number, since it is larger than the sum of its proper divisors (1).

21457199 is an equidigital number, since it uses as much as digits as its factorization.

21457199 is an evil number, because the sum of its binary digits is even.

The product of its digits is 22680, while the sum is 38.

The square root of 21457199 is about 4632.1915979372. The cubic root of 21457199 is about 277.8802470607.

The spelling of 21457199 in words is "twenty-one million, four hundred fifty-seven thousand, one hundred ninety-nine".