21838997 has 4 divisors (see below), whose sum is σ = 22115520. Its totient is φ = 21562476.

The previous prime is 21838967. The next prime is 21839003. The reversal of 21838997 is 79983812.

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 a cyclic number.

It is not a de Polignac number, because 21838997 - 2¹⁴ = 21822613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21838907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 138143 + ... + 138300.

It is an arithmetic number, because the mean of its divisors is an integer number (5528880).

Almost surely, 2^21838997 is an apocalyptic number.

It is an amenable number.

21838997 is a deficient number, since it is larger than the sum of its proper divisors (276523).

21838997 is an equidigital number, since it uses as much as digits as its factorization.

21838997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 276522.

The product of its digits is 217728, while the sum is 47.

The square root of 21838997 is about 4673.2212658936. The cubic root of 21838997 is about 279.5187182845.

The spelling of 21838997 in words is "twenty-one million, eight hundred thirty-eight thousand, nine hundred ninety-seven".