20125691 has 4 divisors (see below), whose sum is σ = 20139432. Its totient is φ = 20111952.

The previous prime is 20125649. The next prime is 20125697. The reversal of 20125691 is 19652102.

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 20125691 - 2⁶ = 20125627 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 20125691.

It is not an unprimeable number, because it can be changed into a prime (20125697) 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, 4370 + ... + 7703.

It is an arithmetic number, because the mean of its divisors is an integer number (5034858).

Almost surely, 2^20125691 is an apocalyptic number.

20125691 is a deficient number, since it is larger than the sum of its proper divisors (13741).

20125691 is a wasteful number, since it uses less digits than its factorization.

20125691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13740.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 20125691 is about 4486.1666264195. The cubic root of 20125691 is about 272.0092043814.

Adding to 20125691 its reverse (19652102), we get a palindrome (39777793).

The spelling of 20125691 in words is "twenty million, one hundred twenty-five thousand, six hundred ninety-one".