21623344373 has 4 divisors (see below), whose sum is σ = 21627064908. Its totient is φ = 21619623840.

The previous prime is 21623344367. The next prime is 21623344411. The reversal of 21623344373 is 37344332612.

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 13362897604 + 8260446769 = 115598^2 + 90887^2 .

It is a cyclic number.

It is not a de Polignac number, because 21623344373 - 2²⁰ = 21622295797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21623340373) 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, 1851536 + ... + 1863177.

It is an arithmetic number, because the mean of its divisors is an integer number (5406766227).

Almost surely, 2^21623344373 is an apocalyptic number.

It is an amenable number.

21623344373 is a deficient number, since it is larger than the sum of its proper divisors (3720535).

21623344373 is an equidigital number, since it uses as much as digits as its factorization.

21623344373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3720534.

The product of its digits is 217728, while the sum is 38.

Adding to 21623344373 its reverse (37344332612), we get a palindrome (58967676985).

The spelling of 21623344373 in words is "twenty-one billion, six hundred twenty-three million, three hundred forty-four thousand, three hundred seventy-three".