21145099 has 4 divisors (see below), whose sum is σ = 21233080. Its totient is φ = 21057120.

The previous prime is 21145079. The next prime is 21145109. The reversal of 21145099 is 99054112.

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 21145099 - 2⁵ = 21145067 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 21145099.

It is not an unprimeable number, because it can be changed into a prime (21145049) 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, 43629 + ... + 44110.

It is an arithmetic number, because the mean of its divisors is an integer number (5308270).

Almost surely, 2^21145099 is an apocalyptic number.

21145099 is a deficient number, since it is larger than the sum of its proper divisors (87981).

21145099 is an equidigital number, since it uses as much as digits as its factorization.

21145099 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87980.

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

The square root of 21145099 is about 4598.3800408405. The cubic root of 21145099 is about 276.5263837780.

The spelling of 21145099 in words is "twenty-one million, one hundred forty-five thousand, ninety-nine".