26821621 has 4 divisors (see below), whose sum is σ = 26832172. Its totient is φ = 26811072.

The previous prime is 26821547. The next prime is 26821643. The reversal of 26821621 is 12612862.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 18584721 + 8236900 = 4311^2 + 2870^2 .

It is a cyclic number.

It is not a de Polignac number, because 26821621 - 2²³ = 18433013 is a prime.

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 26821621.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26821321) 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, 1135 + ... + 7411.

It is an arithmetic number, because the mean of its divisors is an integer number (6708043).

Almost surely, 2^26821621 is an apocalyptic number.

It is an amenable number.

26821621 is a deficient number, since it is larger than the sum of its proper divisors (10551).

26821621 is an equidigital number, since it uses as much as digits as its factorization.

26821621 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10550.

The product of its digits is 2304, while the sum is 28.

The square root of 26821621 is about 5178.9594514729. The cubic root of 26821621 is about 299.3378767548.

The spelling of 26821621 in words is "twenty-six million, eight hundred twenty-one thousand, six hundred twenty-one".