21504199 has 2 divisors, whose sum is σ = 21504200. Its totient is φ = 21504198.

The previous prime is 21504193. The next prime is 21504227. The reversal of 21504199 is 99140512.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21504199 - 2²³ = 13115591 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21504199.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21504193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752099 + 10752100.

It is an arithmetic number, because the mean of its divisors is an integer number (10752100).

Almost surely, 2^21504199 is an apocalyptic number.

21504199 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504199 is an equidigital number, since it uses as much as digits as its factorization.

21504199 is an odious number, because the sum of its binary digits is odd.

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

The square root of 21504199 is about 4637.2620154570. The cubic root of 21504199 is about 278.0829893875.

The spelling of 21504199 in words is "twenty-one million, five hundred four thousand, one hundred ninety-nine".