20787705 has 32 divisors (see below), whose sum is σ = 37825920. Its totient is φ = 10825920.

The previous prime is 20787667. The next prime is 20787709. The reversal of 20787705 is 50778702.

It is not a de Polignac number, because 20787705 - 2¹⁰ = 20786681 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20787705.

It is not an unprimeable number, because it can be changed into a prime (20787709) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4015 + ... + 7595.

It is an arithmetic number, because the mean of its divisors is an integer number (1182060).

Almost surely, 2^20787705 is an apocalyptic number.

It is an amenable number.

20787705 is a deficient number, since it is larger than the sum of its proper divisors (17038215).

20787705 is a wasteful number, since it uses less digits than its factorization.

20787705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3638 (or 3632 counting only the distinct ones).

The product of its (nonzero) digits is 27440, while the sum is 36.

The square root of 20787705 is about 4559.3535726022. The cubic root of 20787705 is about 274.9595753251.

The spelling of 20787705 in words is "twenty million, seven hundred eighty-seven thousand, seven hundred five".