21931443073 has 4 divisors (see below), whose sum is σ = 21931755268. Its totient is φ = 21931130880.

The previous prime is 21931443041. The next prime is 21931443077. The reversal of 21931443073 is 37034413912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 4776468544 + 17154974529 = 69112^2 + 130977^2 .

It is a cyclic number.

It is not a de Polignac number, because 21931443073 - 2⁵ = 21931443041 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21931443077) 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, 4033 + ... + 209473.

It is an arithmetic number, because the mean of its divisors is an integer number (5482938817).

Almost surely, 2^21931443073 is an apocalyptic number.

It is an amenable number.

21931443073 is a deficient number, since it is larger than the sum of its proper divisors (312195).

21931443073 is a wasteful number, since it uses less digits than its factorization.

21931443073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 312194.

The product of its (nonzero) digits is 54432, while the sum is 37.

Adding to 21931443073 its reverse (37034413912), we get a palindrome (58965856985).

The spelling of 21931443073 in words is "twenty-one billion, nine hundred thirty-one million, four hundred forty-three thousand, seventy-three".