21389073 has 16 divisors (see below), whose sum is σ = 29225856. Its totient is φ = 13910400.

The previous prime is 21389063. The next prime is 21389087. The reversal of 21389073 is 37098312.

It is not a de Polignac number, because 21389073 - 2¹⁰ = 21388049 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21389063) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21636 + ... + 22602.

It is an arithmetic number, because the mean of its divisors is an integer number (1826616).

Almost surely, 2^21389073 is an apocalyptic number.

It is an amenable number.

21389073 is a deficient number, since it is larger than the sum of its proper divisors (7836783).

21389073 is a wasteful number, since it uses less digits than its factorization.

21389073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1144.

The product of its (nonzero) digits is 9072, while the sum is 33.

The square root of 21389073 is about 4624.8322131727. The cubic root of 21389073 is about 277.5858479623.

It can be divided in two parts, 2138 and 9073, that added together give a palindrome (11211).

The spelling of 21389073 in words is "twenty-one million, three hundred eighty-nine thousand, seventy-three".