21546389 has 4 divisors (see below), whose sum is σ = 21560556. Its totient is φ = 21532224.

The previous prime is 21546383. The next prime is 21546419. The reversal of 21546389 is 98364512.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 5880625 + 15665764 = 2425^2 + 3958^2 .

It is a cyclic number.

It is not a de Polignac number, because 21546389 - 2⁴ = 21546373 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 (21546383) 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, 4484 + ... + 7949.

It is an arithmetic number, because the mean of its divisors is an integer number (5390139).

Almost surely, 2^21546389 is an apocalyptic number.

It is an amenable number.

21546389 is a deficient number, since it is larger than the sum of its proper divisors (14167).

21546389 is a wasteful number, since it uses less digits than its factorization.

21546389 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14166.

The product of its digits is 51840, while the sum is 38.

The square root of 21546389 is about 4641.8088069200. The cubic root of 21546389 is about 278.2647315202.

The spelling of 21546389 in words is "twenty-one million, five hundred forty-six thousand, three hundred eighty-nine".