20989959 has 4 divisors (see below), whose sum is σ = 27986616. Its totient is φ = 13993304.

The previous prime is 20989957. The next prime is 20989967. The reversal of 20989959 is 95998902.

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 20989959 - 2¹ = 20989957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20989957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3498324 + ... + 3498329.

It is an arithmetic number, because the mean of its divisors is an integer number (6996654).

Almost surely, 2^20989959 is an apocalyptic number.

20989959 is a deficient number, since it is larger than the sum of its proper divisors (6996657).

20989959 is an equidigital number, since it uses as much as digits as its factorization.

20989959 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6996656.

The product of its (nonzero) digits is 524880, while the sum is 51.

The square root of 20989959 is about 4581.4800010477. The cubic root of 20989959 is about 275.8484386317.

The spelling of 20989959 in words is "twenty million, nine hundred eighty-nine thousand, nine hundred fifty-nine".