15725681 has 4 divisors (see below), whose sum is σ = 15742452. Its totient is φ = 15708912.

The previous prime is 15725669. The next prime is 15725701. The reversal of 15725681 is 18652751.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18652751 = 13 ⋅1434827.

It can be written as a sum of positive squares in 2 ways, for example, as 11560000 + 4165681 = 3400^2 + 2041^2 .

It is a cyclic number.

It is not a de Polignac number, because 15725681 - 2¹⁸ = 15463537 is a prime.

It is a super-2 number, since 2×15725681² = 494594085827522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (15725621) 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, 6890 + ... + 8883.

It is an arithmetic number, because the mean of its divisors is an integer number (3935613).

Almost surely, 2^15725681 is an apocalyptic number.

It is an amenable number.

15725681 is a deficient number, since it is larger than the sum of its proper divisors (16771).

15725681 is an equidigital number, since it uses as much as digits as its factorization.

15725681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16770.

The product of its digits is 16800, while the sum is 35.

The square root of 15725681 is about 3965.5618769602. The cubic root of 15725681 is about 250.5358161172.

The spelling of 15725681 in words is "fifteen million, seven hundred twenty-five thousand, six hundred eighty-one".