28705631 has 2 divisors, whose sum is σ = 28705632. Its totient is φ = 28705630.

The previous prime is 28705627. The next prime is 28705657. The reversal of 28705631 is 13650782.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 28705631 - 2² = 28705627 is a prime.

It is a super-2 number, since 2×28705631² = 1648026502216322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28705601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14352815 + 14352816.

It is an arithmetic number, because the mean of its divisors is an integer number (14352816).

Almost surely, 2^28705631 is an apocalyptic number.

28705631 is a deficient number, since it is larger than the sum of its proper divisors (1).

28705631 is an equidigital number, since it uses as much as digits as its factorization.

28705631 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 28705631 is about 5357.7636192725. The cubic root of 28705631 is about 306.1886109910.

The spelling of 28705631 in words is "twenty-eight million, seven hundred five thousand, six hundred thirty-one".