21605123023733 has 4 divisors (see below), whose sum is σ = 21628379346540. Its totient is φ = 21581866700928.

The previous prime is 21605123023699. The next prime is 21605123023747. The reversal of 21605123023733 is 33732032150612.

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 5300341249009 + 16304781774724 = 2302247^2 + 4037918^2 .

It is a cyclic number.

It is not a de Polignac number, because 21605123023733 - 2⁶ = 21605123023669 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 (21605123023933) 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, 11628160010 + ... + 11628161867.

It is an arithmetic number, because the mean of its divisors is an integer number (5407094836635).

Almost surely, 2^{21605123023733} is an apocalyptic number.

It is an amenable number.

21605123023733 is a deficient number, since it is larger than the sum of its proper divisors (23256322807).

21605123023733 is an equidigital number, since it uses as much as digits as its factorization.

21605123023733 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23256322806.

The product of its (nonzero) digits is 136080, while the sum is 38.

The spelling of 21605123023733 in words is "twenty-one trillion, six hundred five billion, one hundred twenty-three million, twenty-three thousand, seven hundred thirty-three".