21100539 has 4 divisors (see below), whose sum is σ = 28134056. Its totient is φ = 14067024.

The previous prime is 21100531. The next prime is 21100543. The reversal of 21100539 is 93500112.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21100539 - 2³ = 21100531 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21100531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3516754 + ... + 3516759.

It is an arithmetic number, because the mean of its divisors is an integer number (7033514).

Almost surely, 2^21100539 is an apocalyptic number.

21100539 is a deficient number, since it is larger than the sum of its proper divisors (7033517).

21100539 is an equidigital number, since it uses as much as digits as its factorization.

21100539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7033516.

The product of its (nonzero) digits is 270, while the sum is 21.

The square root of 21100539 is about 4593.5323009640. The cubic root of 21100539 is about 276.3320017546.

The spelling of 21100539 in words is "twenty-one million, one hundred thousand, five hundred thirty-nine".