21550027865 has 4 divisors (see below), whose sum is σ = 25860033444. Its totient is φ = 17240022288.

The previous prime is 21550027757. The next prime is 21550027871. The reversal of 21550027865 is 56872005512.

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 2291249689 + 19258778176 = 47867^2 + 138776^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21550027865 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2155002782 + ... + 2155002791.

It is an arithmetic number, because the mean of its divisors is an integer number (6465008361).

Almost surely, 2^21550027865 is an apocalyptic number.

It is an amenable number.

21550027865 is a deficient number, since it is larger than the sum of its proper divisors (4310005579).

21550027865 is an equidigital number, since it uses as much as digits as its factorization.

21550027865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4310005578.

The product of its (nonzero) digits is 168000, while the sum is 41.

The spelling of 21550027865 in words is "twenty-one billion, five hundred fifty million, twenty-seven thousand, eight hundred sixty-five".