21356366026 has 4 divisors (see below), whose sum is σ = 32034549042. Its totient is φ = 10678183012.

The previous prime is 21356365999. The next prime is 21356366027. The reversal of 21356366026 is 62066365312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 16409353801 + 4947012225 = 128099^2 + 70335^2 .

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a self number, because there is not a number n which added to its sum of digits gives 21356366026.

It is not an unprimeable number, because it can be changed into a prime (21356366027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5339091505 + ... + 5339091508.

Almost surely, 2^21356366026 is an apocalyptic number.

21356366026 is a deficient number, since it is larger than the sum of its proper divisors (10678183016).

21356366026 is a wasteful number, since it uses less digits than its factorization.

21356366026 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10678183015.

The product of its (nonzero) digits is 233280, while the sum is 40.

The spelling of 21356366026 in words is "twenty-one billion, three hundred fifty-six million, three hundred sixty-six thousand, twenty-six".