20710681 has 4 divisors (see below), whose sum is σ = 20732452. Its totient is φ = 20688912.

The previous prime is 20710673. The next prime is 20710687. The reversal of 20710681 is 18601702.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18705625 + 2005056 = 4325^2 + 1416^2 .

It is a cyclic number.

It is not a de Polignac number, because 20710681 - 2³ = 20710673 is a prime.

It is a super-2 number, since 2×20710681² = 857864614967522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20710687) 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, 9390 + ... + 11383.

It is an arithmetic number, because the mean of its divisors is an integer number (5183113).

Almost surely, 2^20710681 is an apocalyptic number.

It is an amenable number.

20710681 is a deficient number, since it is larger than the sum of its proper divisors (21771).

20710681 is an equidigital number, since it uses as much as digits as its factorization.

20710681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21770.

The product of its (nonzero) digits is 672, while the sum is 25.

The square root of 20710681 is about 4550.8989221911. The cubic root of 20710681 is about 274.6195554652.

The spelling of 20710681 in words is "twenty million, seven hundred ten thousand, six hundred eighty-one".