21573939 has 8 divisors (see below), whose sum is σ = 28868032. Its totient is φ = 14331240.

The previous prime is 21573907. The next prime is 21573971. The reversal of 21573939 is 93937512.

It is an interprime number because it is at equal distance from previous prime (21573907) and next prime (21573971).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21573939 - 2⁵ = 21573907 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21573897 and 21573906.

It is not an unprimeable number, because it can be changed into a prime (21573239) 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 7 ways as a sum of consecutive naturals, for example, 11857 + ... + 13554.

It is an arithmetic number, because the mean of its divisors is an integer number (3608504).

Almost surely, 2^21573939 is an apocalyptic number.

21573939 is a deficient number, since it is larger than the sum of its proper divisors (7294093).

21573939 is a wasteful number, since it uses less digits than its factorization.

21573939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25697.

The product of its digits is 51030, while the sum is 39.

The square root of 21573939 is about 4644.7754520536. The cubic root of 21573939 is about 278.3832808240.

The spelling of 21573939 in words is "twenty-one million, five hundred seventy-three thousand, nine hundred thirty-nine".