21786109145 has 4 divisors (see below), whose sum is σ = 26143330980. Its totient is φ = 17428887312.

The previous prime is 21786109141. The next prime is 21786109193. The reversal of 21786109145 is 54190168712.

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 13258140736 + 8527968409 = 115144^2 + 92347^2 .

It is a cyclic number.

It is not a de Polignac number, because 21786109145 - 2² = 21786109141 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21786109096 and 21786109105.

It is not an unprimeable number, because it can be changed into a prime (21786109141) 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, 2178610910 + ... + 2178610919.

It is an arithmetic number, because the mean of its divisors is an integer number (6535832745).

Almost surely, 2^21786109145 is an apocalyptic number.

It is an amenable number.

21786109145 is a deficient number, since it is larger than the sum of its proper divisors (4357221835).

21786109145 is an equidigital number, since it uses as much as digits as its factorization.

21786109145 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4357221834.

The product of its (nonzero) digits is 120960, while the sum is 44.

The spelling of 21786109145 in words is "twenty-one billion, seven hundred eighty-six million, one hundred nine thousand, one hundred forty-five".