20391633 has 6 divisors (see below), whose sum is σ = 29454594. Its totient is φ = 13594416.

The previous prime is 20391599. The next prime is 20391647. The reversal of 20391633 is 33619302.

20391633 is a `hidden beast` number, since 20 + 3 + 9 + 1 + 633 = 666.

It can be written as a sum of positive squares in only one way, i.e., 20358144 + 33489 = 4512^2 + 183^2 .

It is not a de Polignac number, because 20391633 - 2⁸ = 20391377 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 20391597 and 20391606.

It is not an unprimeable number, because it can be changed into a prime (20391433) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1132860 + ... + 1132877.

It is an arithmetic number, because the mean of its divisors is an integer number (4909099).

Almost surely, 2^20391633 is an apocalyptic number.

It is an amenable number.

20391633 is a deficient number, since it is larger than the sum of its proper divisors (9062961).

20391633 is a wasteful number, since it uses less digits than its factorization.

20391633 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2265743 (or 2265740 counting only the distinct ones).

The product of its (nonzero) digits is 2916, while the sum is 27.

The square root of 20391633 is about 4515.7095787927. The cubic root of 20391633 is about 273.2020803833.

The spelling of 20391633 in words is "twenty million, three hundred ninety-one thousand, six hundred thirty-three".