20125681 has 4 divisors (see below), whose sum is σ = 20819700. Its totient is φ = 19431664.

The previous prime is 20125649. The next prime is 20125697. The reversal of 20125681 is 18652102.

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 17181025 + 2944656 = 4145^2 + 1716^2 .

It is a cyclic number.

It is not a de Polignac number, because 20125681 - 2⁵ = 20125649 is a prime.

It is a super-2 number, since 2×20125681² = 810086071427522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20125601) 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, 346966 + ... + 347023.

It is an arithmetic number, because the mean of its divisors is an integer number (5204925).

Almost surely, 2^20125681 is an apocalyptic number.

It is an amenable number.

20125681 is a deficient number, since it is larger than the sum of its proper divisors (694019).

20125681 is an equidigital number, since it uses as much as digits as its factorization.

20125681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 694018.

The product of its (nonzero) digits is 960, while the sum is 25.

The square root of 20125681 is about 4486.1655118821. The cubic root of 20125681 is about 272.0091593297.

Adding to 20125681 its reverse (18652102), we get a palindrome (38777783).

The spelling of 20125681 in words is "twenty million, one hundred twenty-five thousand, six hundred eighty-one".