13825781 has 4 divisors (see below), whose sum is σ = 13903200. Its totient is φ = 13748364.

The previous prime is 13825771. The next prime is 13825807. The reversal of 13825781 is 18752831.

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 13825781 - 2⁶ = 13825717 is a prime.

It is a super-2 number, since 2×13825781² = 382304440519922, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (13825741) 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, 38441 + ... + 38798.

It is an arithmetic number, because the mean of its divisors is an integer number (3475800).

Almost surely, 2^13825781 is an apocalyptic number.

It is an amenable number.

13825781 is a deficient number, since it is larger than the sum of its proper divisors (77419).

13825781 is an equidigital number, since it uses as much as digits as its factorization.

13825781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 77418.

The product of its digits is 13440, while the sum is 35.

The square root of 13825781 is about 3718.3035110114. The cubic root of 13825781 is about 240.0103062704.

It can be divided in two parts, 138 and 25781, that multiplied together give a triangular number (3557778 = T₂₆₆₇).

The spelling of 13825781 in words is "thirteen million, eight hundred twenty-five thousand, seven hundred eighty-one".