21390099 has 16 divisors (see below), whose sum is σ = 29113344. Its totient is φ = 13966400.

The previous prime is 21390091. The next prime is 21390101. The reversal of 21390099 is 99009312.

It is a cyclic number.

It is not a de Polignac number, because 21390099 - 2³ = 21390091 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21390091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 49414 + ... + 49844.

It is an arithmetic number, because the mean of its divisors is an integer number (1819584).

Almost surely, 2^21390099 is an apocalyptic number.

21390099 is a deficient number, since it is larger than the sum of its proper divisors (7723245).

21390099 is a wasteful number, since it uses less digits than its factorization.

21390099 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738.

The product of its (nonzero) digits is 4374, while the sum is 33.

The square root of 21390099 is about 4624.9431347856. The cubic root of 21390099 is about 277.5902863427.

The spelling of 21390099 in words is "twenty-one million, three hundred ninety thousand, ninety-nine".