21393489 has 16 divisors (see below), whose sum is σ = 31435712. Its totient is φ = 12858048.

The previous prime is 21393481. The next prime is 21393521. The reversal of 21393489 is 98439312.

It is not a de Polignac number, because 21393489 - 2³ = 21393481 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21393481) 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, 4702 + ... + 8055.

It is an arithmetic number, because the mean of its divisors is an integer number (1964732).

Almost surely, 2^21393489 is an apocalyptic number.

It is an amenable number.

21393489 is a deficient number, since it is larger than the sum of its proper divisors (10042223).

21393489 is a wasteful number, since it uses less digits than its factorization.

21393489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12816.

The product of its digits is 46656, while the sum is 39.

The square root of 21393489 is about 4625.3096112585. The cubic root of 21393489 is about 277.6049501577.

The spelling of 21393489 in words is "twenty-one million, three hundred ninety-three thousand, four hundred eighty-nine".