21368673 has 18 divisors (see below), whose sum is σ = 32580834. Its totient is φ = 13493952.

The previous prime is 21368651. The next prime is 21368707. The reversal of 21368673 is 37686312.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 21316689 + 51984 = 4617^2 + 228^2 .

It is not a de Polignac number, because 21368673 - 2¹³ = 21360481 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21360673) 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 17 ways as a sum of consecutive naturals, for example, 40 + ... + 6537.

Almost surely, 2^21368673 is an apocalyptic number.

It is an amenable number.

21368673 is a deficient number, since it is larger than the sum of its proper divisors (11212161).

21368673 is a wasteful number, since it uses less digits than its factorization.

21368673 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6621 (or 6599 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 21368673 is about 4622.6262016304. The cubic root of 21368673 is about 277.4975699812.

It can be divided in two parts, 213 and 68673, that added together give a palindrome (68886).

The spelling of 21368673 in words is "twenty-one million, three hundred sixty-eight thousand, six hundred seventy-three".