21228840673 has 4 divisors (see below), whose sum is σ = 21230677188. Its totient is φ = 21227004160.

The previous prime is 21228840653. The next prime is 21228840683. The reversal of 21228840673 is 37604882212.

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 15822620944 + 5406219729 = 125788^2 + 73527^2 .

It is a cyclic number.

It is not a de Polignac number, because 21228840673 - 2¹³ = 21228832481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21228840653) 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, 900808 + ... + 924073.

It is an arithmetic number, because the mean of its divisors is an integer number (5307669297).

Almost surely, 2^21228840673 is an apocalyptic number.

It is an amenable number.

21228840673 is a deficient number, since it is larger than the sum of its proper divisors (1836515).

21228840673 is a wasteful number, since it uses less digits than its factorization.

21228840673 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1836514.

The product of its (nonzero) digits is 258048, while the sum is 43.

The spelling of 21228840673 in words is "twenty-one billion, two hundred twenty-eight million, eight hundred forty thousand, six hundred seventy-three".