21412399 has 4 divisors (see below), whose sum is σ = 21480264. Its totient is φ = 21344536.

The previous prime is 21412387. The next prime is 21412429. The reversal of 21412399 is 99321412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21412399 - 2¹¹ = 21410351 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21412399.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21412309) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 33457 + ... + 34090.

It is an arithmetic number, because the mean of its divisors is an integer number (5370066).

Almost surely, 2^21412399 is an apocalyptic number.

21412399 is a deficient number, since it is larger than the sum of its proper divisors (67865).

21412399 is an equidigital number, since it uses as much as digits as its factorization.

21412399 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 67864.

The product of its digits is 3888, while the sum is 31.

The square root of 21412399 is about 4627.3533472170. The cubic root of 21412399 is about 277.6867190183.

The spelling of 21412399 in words is "twenty-one million, four hundred twelve thousand, three hundred ninety-nine".