21690789121 has 8 divisors (see below), whose sum is σ = 21769922664. Its totient is φ = 21611690880.

The previous prime is 21690789119. The next prime is 21690789137. The reversal of 21690789121 is 12198709612.

It can be written as a sum of positive squares in 4 ways, for example, as 11156640625 + 10534148496 = 105625^2 + 102636^2 .

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 21690789121 - 2¹ = 21690789119 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21690789161) 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, 2204605 + ... + 2214421.

It is an arithmetic number, because the mean of its divisors is an integer number (2721240333).

Almost surely, 2^21690789121 is an apocalyptic number.

It is an amenable number.

21690789121 is a deficient number, since it is larger than the sum of its proper divisors (79133543).

21690789121 is an equidigital number, since it uses as much as digits as its factorization.

21690789121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17651.

The product of its (nonzero) digits is 108864, while the sum is 46.

The spelling of 21690789121 in words is "twenty-one billion, six hundred ninety million, seven hundred eighty-nine thousand, one hundred twenty-one".