21135799909 has 8 divisors (see below), whose sum is σ = 24460962560. Its totient is φ = 17887077936.

The previous prime is 21135799897. The next prime is 21135799931. The reversal of 21135799909 is 90999753112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21135799909 - 2⁹ = 21135799397 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 21135799909.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21135799999) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19109574 + ... + 19110679.

It is an arithmetic number, because the mean of its divisors is an integer number (3057620320).

Almost surely, 2^21135799909 is an apocalyptic number.

It is an amenable number.

21135799909 is a deficient number, since it is larger than the sum of its proper divisors (3325162651).

21135799909 is an equidigital number, since it uses as much as digits as its factorization.

21135799909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38220339.

The product of its (nonzero) digits is 1377810, while the sum is 55.

The spelling of 21135799909 in words is "twenty-one billion, one hundred thirty-five million, seven hundred ninety-nine thousand, nine hundred nine".