21227135721 has 16 divisors (see below), whose sum is σ = 30883845888. Its totient is φ = 12861592400.

The previous prime is 21227135719. The next prime is 21227135807. The reversal of 21227135721 is 12753172212.

It is a cyclic number.

It is not a de Polignac number, because 21227135721 - 2¹ = 21227135719 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is not an unprimeable number, because it can be changed into a prime (21227175721) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 48766 + ... + 211736.

It is an arithmetic number, because the mean of its divisors is an integer number (1930240368).

Almost surely, 2^21227135721 is an apocalyptic number.

It is an amenable number.

21227135721 is a deficient number, since it is larger than the sum of its proper divisors (9656710167).

21227135721 is a wasteful number, since it uses less digits than its factorization.

21227135721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166932.

The product of its digits is 11760, while the sum is 33.

The spelling of 21227135721 in words is "twenty-one billion, two hundred twenty-seven million, one hundred thirty-five thousand, seven hundred twenty-one".