20771999 has 4 divisors (see below), whose sum is σ = 20955936. Its totient is φ = 20588064.

The previous prime is 20771987. The next prime is 20772019. The reversal of 20771999 is 99917702.

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 20771999 - 2⁴ = 20771983 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 (20771929) 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, 91799 + ... + 92024.

It is an arithmetic number, because the mean of its divisors is an integer number (5238984).

Almost surely, 2^20771999 is an apocalyptic number.

20771999 is a deficient number, since it is larger than the sum of its proper divisors (183937).

20771999 is a wasteful number, since it uses less digits than its factorization.

20771999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183936.

The product of its (nonzero) digits is 71442, while the sum is 44.

The square root of 20771999 is about 4557.6308538538. The cubic root of 20771999 is about 274.8903099725.

The spelling of 20771999 in words is "twenty million, seven hundred seventy-one thousand, nine hundred ninety-nine".