28726581 has 16 divisors (see below), whose sum is σ = 41368320. Its totient is φ = 17626560.

The previous prime is 28726573. The next prime is 28726589. The reversal of 28726581 is 18562782.

It is an interprime number because it is at equal distance from previous prime (28726573) and next prime (28726589).

It is not a de Polignac number, because 28726581 - 2³ = 28726573 is a prime.

It is a super-2 number, since 2×28726581² = 1650432911899122, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28726589) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15955 + ... + 17663.

It is an arithmetic number, because the mean of its divisors is an integer number (2585520).

Almost surely, 2^28726581 is an apocalyptic number.

It is an amenable number.

28726581 is a deficient number, since it is larger than the sum of its proper divisors (12641739).

28726581 is a wasteful number, since it uses less digits than its factorization.

28726581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2156.

The product of its digits is 53760, while the sum is 39.

The square root of 28726581 is about 5359.7183694668. The cubic root of 28726581 is about 306.2630806019.

It can be divided in two parts, 2872 and 6581, that added together give a triangular number (9453 = T₁₃₇).

The spelling of 28726581 in words is "twenty-eight million, seven hundred twenty-six thousand, five hundred eighty-one".