21778415321 has 4 divisors (see below), whose sum is σ = 23453678052. Its totient is φ = 20103152592.

The previous prime is 21778415299. The next prime is 21778415357. The reversal of 21778415321 is 12351487712.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7632643225 + 14145772096 = 87365^2 + 118936^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21778415321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21778615321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 837631346 + ... + 837631371.

It is an arithmetic number, because the mean of its divisors is an integer number (5863419513).

Almost surely, 2^21778415321 is an apocalyptic number.

It is an amenable number.

21778415321 is a deficient number, since it is larger than the sum of its proper divisors (1675262731).

21778415321 is a wasteful number, since it uses less digits than its factorization.

21778415321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1675262730.

The product of its digits is 94080, while the sum is 41.

The spelling of 21778415321 in words is "twenty-one billion, seven hundred seventy-eight million, four hundred fifteen thousand, three hundred twenty-one".