28891631 has 2 divisors, whose sum is σ = 28891632. Its totient is φ = 28891630.

The previous prime is 28891607. The next prime is 28891633. The reversal of 28891631 is 13619882.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 28891631 - 2¹⁴ = 28875247 is a prime.

It is a super-2 number, since 2×28891631² = 1669452683680322, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 28891633, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28891633) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14445815 + 14445816.

It is an arithmetic number, because the mean of its divisors is an integer number (14445816).

Almost surely, 2^28891631 is an apocalyptic number.

28891631 is a deficient number, since it is larger than the sum of its proper divisors (1).

28891631 is an equidigital number, since it uses as much as digits as its factorization.

28891631 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 38.

The square root of 28891631 is about 5375.0935805807. The cubic root of 28891631 is about 306.8485107444.

It can be divided in two parts, 288 and 91631, that added together give a palindrome (91919).

The spelling of 28891631 in words is "twenty-eight million, eight hundred ninety-one thousand, six hundred thirty-one".