26651666021 has 4 divisors (see below), whose sum is σ = 26664139692. Its totient is φ = 26639192352.

The previous prime is 26651666011. The next prime is 26651666039. The reversal of 26651666021 is 12066615662.

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 1884775396 + 24766890625 = 43414^2 + 157375^2 .

It is a de Polignac number, because none of the positive numbers 2^k-26651666021 is a prime.

It is a super-2 number, since 2×26651666021² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 26651666021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26651666011) 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, 6233630 + ... + 6237903.

It is an arithmetic number, because the mean of its divisors is an integer number (6666034923).

Almost surely, 2^26651666021 is an apocalyptic number.

It is an amenable number.

26651666021 is a deficient number, since it is larger than the sum of its proper divisors (12473671).

26651666021 is a wasteful number, since it uses less digits than its factorization.

26651666021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12473670.

The product of its (nonzero) digits is 155520, while the sum is 41.

The spelling of 26651666021 in words is "twenty-six billion, six hundred fifty-one million, six hundred sixty-six thousand, twenty-one".