21242499 has 4 divisors (see below), whose sum is σ = 28323336. Its totient is φ = 14161664.

The previous prime is 21242491. The next prime is 21242509. The reversal of 21242499 is 99424212.

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 21242499 - 2³ = 21242491 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21242491) 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, 3540414 + ... + 3540419.

It is an arithmetic number, because the mean of its divisors is an integer number (7080834).

Almost surely, 2^21242499 is an apocalyptic number.

21242499 is a deficient number, since it is larger than the sum of its proper divisors (7080837).

21242499 is an equidigital number, since it uses as much as digits as its factorization.

21242499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7080836.

The product of its digits is 10368, while the sum is 33.

The square root of 21242499 is about 4608.9585591541. The cubic root of 21242499 is about 276.9503184324.

The spelling of 21242499 in words is "twenty-one million, two hundred forty-two thousand, four hundred ninety-nine".