20817613 has 4 divisors (see below), whose sum is σ = 20967520. Its totient is φ = 20667708.

The previous prime is 20817611. The next prime is 20817623. The reversal of 20817613 is 31671802.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20817613 - 2¹ = 20817611 is a prime.

It is a super-2 number, since 2×20817613² = 866746022035538, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20817611) 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, 74745 + ... + 75022.

It is an arithmetic number, because the mean of its divisors is an integer number (5241880).

Almost surely, 2^20817613 is an apocalyptic number.

It is an amenable number.

20817613 is a deficient number, since it is larger than the sum of its proper divisors (149907).

20817613 is a wasteful number, since it uses less digits than its factorization.

20817613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 149906.

The product of its (nonzero) digits is 2016, while the sum is 28.

The square root of 20817613 is about 4562.6322446588. The cubic root of 20817613 is about 275.0913767966.

The spelling of 20817613 in words is "twenty million, eight hundred seventeen thousand, six hundred thirteen".