20671787 has 4 divisors (see below), whose sum is σ = 20687160. Its totient is φ = 20656416.

The previous prime is 20671769. The next prime is 20671811. The reversal of 20671787 is 78717602.

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 20671787 - 2⁶ = 20671723 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20671787.

It is not an unprimeable number, because it can be changed into a prime (20671757) 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, 5453 + ... + 8430.

It is an arithmetic number, because the mean of its divisors is an integer number (5171790).

Almost surely, 2^20671787 is an apocalyptic number.

20671787 is a deficient number, since it is larger than the sum of its proper divisors (15373).

20671787 is a wasteful number, since it uses less digits than its factorization.

20671787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15372.

The product of its (nonzero) digits is 32928, while the sum is 38.

The square root of 20671787 is about 4546.6236923678. The cubic root of 20671787 is about 274.4475388103.

The spelling of 20671787 in words is "twenty million, six hundred seventy-one thousand, seven hundred eighty-seven".