28941781 has 4 divisors (see below), whose sum is σ = 31572864. Its totient is φ = 26310700.

The previous prime is 28941779. The next prime is 28941823. The reversal of 28941781 is 18714982.

It is a happy number.

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 28941781 - 2¹ = 28941779 is a prime.

It is a super-2 number, since 2×28941781² = 1675253374903922, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28941181) 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, 1315525 + ... + 1315546.

It is an arithmetic number, because the mean of its divisors is an integer number (7893216).

Almost surely, 2^28941781 is an apocalyptic number.

It is an amenable number.

28941781 is a deficient number, since it is larger than the sum of its proper divisors (2631083).

28941781 is a wasteful number, since it uses less digits than its factorization.

28941781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2631082.

The product of its digits is 32256, while the sum is 40.

The square root of 28941781 is about 5379.7565930068. The cubic root of 28941781 is about 307.0259503364.

The spelling of 28941781 in words is "twenty-eight million, nine hundred forty-one thousand, seven hundred eighty-one".