21665738093 has 8 divisors (see below), whose sum is σ = 23018585880. Its totient is φ = 20353273920.

The previous prime is 21665738069. The next prime is 21665738113. The reversal of 21665738093 is 39083756612.

It can be written as a sum of positive squares in 4 ways, for example, as 9900648004 + 11765090089 = 99502^2 + 108467^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21665738093 - 2¹⁶ = 21665672557 is a prime.

It is a super-2 number, since 2×21665738093² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21665738023) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10094798 + ... + 10096943.

It is an arithmetic number, because the mean of its divisors is an integer number (2877323235).

Almost surely, 2^21665738093 is an apocalyptic number.

It is an amenable number.

21665738093 is a deficient number, since it is larger than the sum of its proper divisors (1352847787).

21665738093 is a wasteful number, since it uses less digits than its factorization.

21665738093 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20191807.

The product of its (nonzero) digits is 1632960, while the sum is 50.

The spelling of 21665738093 in words is "twenty-one billion, six hundred sixty-five million, seven hundred thirty-eight thousand, ninety-three".