20731617 has 6 divisors (see below), whose sum is σ = 29945682. Its totient is φ = 13821072.

The previous prime is 20731589. The next prime is 20731637. The reversal of 20731617 is 71613702.

It can be written as a sum of positive squares in only one way, i.e., 15492096 + 5239521 = 3936^2 + 2289^2 .

It is not a de Polignac number, because 20731617 - 2⁶ = 20731553 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20731637) 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, 1151748 + ... + 1151765.

It is an arithmetic number, because the mean of its divisors is an integer number (4990947).

Almost surely, 2^20731617 is an apocalyptic number.

It is an amenable number.

20731617 is a deficient number, since it is larger than the sum of its proper divisors (9214065).

20731617 is a wasteful number, since it uses less digits than its factorization.

20731617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2303519 (or 2303516 counting only the distinct ones).

The product of its (nonzero) digits is 1764, while the sum is 27.

The square root of 20731617 is about 4553.1985460773. The cubic root of 20731617 is about 274.7120600489.

The spelling of 20731617 in words is "twenty million, seven hundred thirty-one thousand, six hundred seventeen".