21428773 has 8 divisors (see below), whose sum is σ = 22097880. Its totient is φ = 20766720.

The previous prime is 21428747. The next prime is 21428791. The reversal of 21428773 is 37782412.

It can be written as a sum of positive squares in 4 ways, for example, as 56644 + 21372129 = 238^2 + 4623^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21428773 - 2²¹ = 19331621 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 (21425773) 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 7 ways as a sum of consecutive naturals, for example, 4773 + ... + 8101.

It is an arithmetic number, because the mean of its divisors is an integer number (2762235).

Almost surely, 2^21428773 is an apocalyptic number.

It is an amenable number.

21428773 is a deficient number, since it is larger than the sum of its proper divisors (669107).

21428773 is a wasteful number, since it uses less digits than its factorization.

21428773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3527.

The product of its digits is 18816, while the sum is 34.

The square root of 21428773 is about 4629.1222710142. The cubic root of 21428773 is about 277.7574830625.

It can be divided in two parts, 21428 and 773, that added together give a square (22201 = 149²).

The spelling of 21428773 in words is "twenty-one million, four hundred twenty-eight thousand, seven hundred seventy-three".