21315820909 has 8 divisors (see below), whose sum is σ = 22448132480. Its totient is φ = 20184552000.

The previous prime is 21315820873. The next prime is 21315820919. The reversal of 21315820909 is 90902851312.

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

It is a cyclic number.

It is not a de Polignac number, because 21315820909 - 2⁹ = 21315820397 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21315820919) 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, 218517 + ... + 300634.

It is an arithmetic number, because the mean of its divisors is an integer number (2806016560).

Almost surely, 2^21315820909 is an apocalyptic number.

It is an amenable number.

21315820909 is a deficient number, since it is larger than the sum of its proper divisors (1132311571).

21315820909 is a wasteful number, since it uses less digits than its factorization.

21315820909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 521331.

The product of its (nonzero) digits is 38880, while the sum is 40.

The spelling of 21315820909 in words is "twenty-one billion, three hundred fifteen million, eight hundred twenty thousand, nine hundred nine".