26820021 has 4 divisors (see below), whose sum is σ = 35760032. Its totient is φ = 17880012.

The previous prime is 26820019. The next prime is 26820097. The reversal of 26820021 is 12002862.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 26820021 - 2¹ = 26820019 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 26820021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (26820121) 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, 4470001 + ... + 4470006.

It is an arithmetic number, because the mean of its divisors is an integer number (8940008).

Almost surely, 2^26820021 is an apocalyptic number.

It is an amenable number.

26820021 is a deficient number, since it is larger than the sum of its proper divisors (8940011).

26820021 is an equidigital number, since it uses as much as digits as its factorization.

26820021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8940010.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 26820021 is about 5178.8049779848. The cubic root of 26820021 is about 299.3319244657.

Adding to 26820021 its reverse (12002862), we get a palindrome (38822883).

The spelling of 26820021 in words is "twenty-six million, eight hundred twenty thousand, twenty-one".