21438773 has 4 divisors (see below), whose sum is σ = 21465708. Its totient is φ = 21411840.

The previous prime is 21438757. The next prime is 21438779. The reversal of 21438773 is 37783412.

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 9591409 + 11847364 = 3097^2 + 3442^2 .

It is a cyclic number.

It is not a de Polignac number, because 21438773 - 2⁴ = 21438757 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 (21438779) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12236 + ... + 13877.

It is an arithmetic number, because the mean of its divisors is an integer number (5366427).

Almost surely, 2^21438773 is an apocalyptic number.

It is an amenable number.

21438773 is a deficient number, since it is larger than the sum of its proper divisors (26935).

21438773 is an equidigital number, since it uses as much as digits as its factorization.

21438773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26934.

The product of its digits is 28224, while the sum is 35.

The square root of 21438773 is about 4630.2022634006. The cubic root of 21438773 is about 277.8006826565.

The spelling of 21438773 in words is "twenty-one million, four hundred thirty-eight thousand, seven hundred seventy-three".