20556239 has 4 divisors (see below), whose sum is σ = 22425000. Its totient is φ = 18687480.

The previous prime is 20556223. The next prime is 20556269. The reversal of 20556239 is 93265502.

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

It is a cyclic number.

It is not a de Polignac number, because 20556239 - 2⁴ = 20556223 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 (20556269) 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, 934364 + ... + 934385.

It is an arithmetic number, because the mean of its divisors is an integer number (5606250).

Almost surely, 2^20556239 is an apocalyptic number.

20556239 is a deficient number, since it is larger than the sum of its proper divisors (1868761).

20556239 is a wasteful number, since it uses less digits than its factorization.

20556239 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1868760.

The product of its (nonzero) digits is 16200, while the sum is 32.

The square root of 20556239 is about 4533.8988740377. The cubic root of 20556239 is about 273.9352280873.

The spelling of 20556239 in words is "twenty million, five hundred fifty-six thousand, two hundred thirty-nine".