21515099 has 2 divisors, whose sum is σ = 21515100. Its totient is φ = 21515098.

The previous prime is 21515083. The next prime is 21515113. The reversal of 21515099 is 99051512.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21515099 - 2⁴ = 21515083 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21515009) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10757549 + 10757550.

It is an arithmetic number, because the mean of its divisors is an integer number (10757550).

Almost surely, 2^21515099 is an apocalyptic number.

21515099 is a deficient number, since it is larger than the sum of its proper divisors (1).

21515099 is an equidigital number, since it uses as much as digits as its factorization.

21515099 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4050, while the sum is 32.

The square root of 21515099 is about 4638.4371290339. The cubic root of 21515099 is about 278.1299661445.

The spelling of 21515099 in words is "twenty-one million, five hundred fifteen thousand, ninety-nine".