21728521412 has 12 divisors (see below), whose sum is σ = 40949905836. Its totient is φ = 10028548320.

The previous prime is 21728521343. The next prime is 21728521421. The reversal of 21728521412 is 21412582712.

It can be written as a sum of positive squares in 2 ways, for example, as 3674299456 + 18054221956 = 60616^2 + 134366^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 208928039 + ... + 208928142.

It is an arithmetic number, because the mean of its divisors is an integer number (3412492153).

Almost surely, 2^21728521412 is an apocalyptic number.

It is an amenable number.

21728521412 is a deficient number, since it is larger than the sum of its proper divisors (19221384424).

21728521412 is a wasteful number, since it uses less digits than its factorization.

21728521412 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 417856198 (or 417856196 counting only the distinct ones).

The product of its digits is 17920, while the sum is 35.

The spelling of 21728521412 in words is "twenty-one billion, seven hundred twenty-eight million, five hundred twenty-one thousand, four hundred twelve".