21573889 has 4 divisors (see below), whose sum is σ = 21588820. Its totient is φ = 21558960.

The previous prime is 21573887. The next prime is 21573907. The reversal of 21573889 is 98837512.

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 6426225 + 15147664 = 2535^2 + 3892^2 .

It is a cyclic number.

It is not a de Polignac number, because 21573889 - 2¹ = 21573887 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21573887) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5034 + ... + 8275.

It is an arithmetic number, because the mean of its divisors is an integer number (5397205).

Almost surely, 2^21573889 is an apocalyptic number.

It is an amenable number.

21573889 is a deficient number, since it is larger than the sum of its proper divisors (14931).

21573889 is a wasteful number, since it uses less digits than its factorization.

21573889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14930.

The product of its digits is 120960, while the sum is 43.

The square root of 21573889 is about 4644.7700696590. The cubic root of 21573889 is about 278.3830657624.

The spelling of 21573889 in words is "twenty-one million, five hundred seventy-three thousand, eight hundred eighty-nine".