21201101509 has 6 divisors (see below), whose sum is σ = 24662505894. Its totient is φ = 18172372680.

The previous prime is 21201101479. The next prime is 21201101513. The reversal of 21201101509 is 90510110212.

It can be written as a sum of positive squares in only one way, i.e., 18622696225 + 2578405284 = 136465^2 + 50778^2 .

It is not a de Polignac number, because 21201101509 - 2⁷ = 21201101381 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 21201101509.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201101809) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 216337722 + ... + 216337819.

It is an arithmetic number, because the mean of its divisors is an integer number (4110417649).

Almost surely, 2^21201101509 is an apocalyptic number.

It is an amenable number.

21201101509 is a deficient number, since it is larger than the sum of its proper divisors (3461404385).

21201101509 is an equidigital number, since it uses as much as digits as its factorization.

21201101509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 432675555 (or 432675548 counting only the distinct ones).

The product of its (nonzero) digits is 180, while the sum is 22.

The spelling of 21201101509 in words is "twenty-one billion, two hundred one million, one hundred one thousand, five hundred nine".