21129773 has 4 divisors (see below), whose sum is σ = 24148320. Its totient is φ = 18111228.

The previous prime is 21129761. The next prime is 21129781. The reversal of 21129773 is 37792112.

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 21129773 - 2²⁰ = 20081197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21129673) 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, 1509263 + ... + 1509276.

It is an arithmetic number, because the mean of its divisors is an integer number (6037080).

Almost surely, 2^21129773 is an apocalyptic number.

It is an amenable number.

21129773 is a deficient number, since it is larger than the sum of its proper divisors (3018547).

21129773 is an equidigital number, since it uses as much as digits as its factorization.

21129773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3018546.

The product of its digits is 5292, while the sum is 32.

The square root of 21129773 is about 4596.7132823355. The cubic root of 21129773 is about 276.4595587155.

The spelling of 21129773 in words is "twenty-one million, one hundred twenty-nine thousand, seven hundred seventy-three".