21540499 has 4 divisors (see below), whose sum is σ = 21762664. Its totient is φ = 21318336.

The previous prime is 21540473. The next prime is 21540529. The reversal of 21540499 is 99404512.

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 21540499 - 2¹³ = 21532307 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21540439) 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, 110937 + ... + 111130.

It is an arithmetic number, because the mean of its divisors is an integer number (5440666).

Almost surely, 2^21540499 is an apocalyptic number.

21540499 is a deficient number, since it is larger than the sum of its proper divisors (222165).

21540499 is an equidigital number, since it uses as much as digits as its factorization.

21540499 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 222164.

The product of its (nonzero) digits is 12960, while the sum is 34.

The square root of 21540499 is about 4641.1743126067. The cubic root of 21540499 is about 278.2393733865.

The spelling of 21540499 in words is "twenty-one million, five hundred forty thousand, four hundred ninety-nine".