21990499 has 4 divisors (see below), whose sum is σ = 22061520. Its totient is φ = 21919480.

The previous prime is 21990491. The next prime is 21990509. The reversal of 21990499 is 99409912.

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 21990499 - 2³ = 21990491 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21990491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 35044 + ... + 35665.

It is an arithmetic number, because the mean of its divisors is an integer number (5515380).

Almost surely, 2^21990499 is an apocalyptic number.

21990499 is a deficient number, since it is larger than the sum of its proper divisors (71021).

21990499 is an equidigital number, since it uses as much as digits as its factorization.

21990499 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71020.

The product of its (nonzero) digits is 52488, while the sum is 43.

The square root of 21990499 is about 4689.4028404478. The cubic root of 21990499 is about 280.1635906277.

The spelling of 21990499 in words is "twenty-one million, nine hundred ninety thousand, four hundred ninety-nine".