20647975 has 6 divisors (see below), whose sum is σ = 25603520. Its totient is φ = 16518360.

The previous prime is 20647967. The next prime is 20647981. The reversal of 20647975 is 57974602.

It is not a de Polignac number, because 20647975 - 2³ = 20647967 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 412935 + ... + 412984.

Almost surely, 2^20647975 is an apocalyptic number.

20647975 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

20647975 is a deficient number, since it is larger than the sum of its proper divisors (4955545).

20647975 is an equidigital number, since it uses as much as digits as its factorization.

20647975 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 825929 (or 825924 counting only the distinct ones).

The product of its (nonzero) digits is 105840, while the sum is 40.

The square root of 20647975 is about 4544.0042913712. The cubic root of 20647975 is about 274.3421188693.

The spelling of 20647975 in words is "twenty million, six hundred forty-seven thousand, nine hundred seventy-five".