20921155009 has 8 divisors (see below), whose sum is σ = 22159159848. Its totient is φ = 19683966720.

The previous prime is 20921155001. The next prime is 20921155033. The reversal of 20921155009 is 90055112902.

It can be written as a sum of positive squares in 4 ways, for example, as 9511710784 + 11409444225 = 97528^2 + 106815^2 .

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 20921155009 - 2³ = 20921155001 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20921155001) 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, 150982 + ... + 254239.

It is an arithmetic number, because the mean of its divisors is an integer number (2769894981).

Almost surely, 2^20921155009 is an apocalyptic number.

It is an amenable number.

20921155009 is a deficient number, since it is larger than the sum of its proper divisors (1238004839).

20921155009 is a wasteful number, since it uses less digits than its factorization.

20921155009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 408275.

The product of its (nonzero) digits is 8100, while the sum is 34.

The spelling of 20921155009 in words is "twenty billion, nine hundred twenty-one million, one hundred fifty-five thousand, nine".