20681767 has 4 divisors (see below), whose sum is σ = 20813656. Its totient is φ = 20549880.

The previous prime is 20681723. The next prime is 20681777. The reversal of 20681767 is 76718602.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20681767 - 2¹¹ = 20679719 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20681777) 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 3 ways as a sum of consecutive naturals, for example, 65709 + ... + 66022.

It is an arithmetic number, because the mean of its divisors is an integer number (5203414).

Almost surely, 2^20681767 is an apocalyptic number.

20681767 is a deficient number, since it is larger than the sum of its proper divisors (131889).

20681767 is a wasteful number, since it uses less digits than its factorization.

20681767 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131888.

The product of its (nonzero) digits is 28224, while the sum is 37.

The square root of 20681767 is about 4547.7210776388. The cubic root of 20681767 is about 274.4916979627.

The spelling of 20681767 in words is "twenty million, six hundred eighty-one thousand, seven hundred sixty-seven".