28001631 has 8 divisors (see below), whose sum is σ = 42669184. Its totient is φ = 16000920.

The previous prime is 28001621. The next prime is 28001651. The reversal of 28001631 is 13610082.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28001631 - 2¹¹ = 27999583 is a prime.

It is a super-2 number, since 2×28001631² = 1568182677320322, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21), and also a Moran number because the ratio is a prime number: 1333411 = 28001631 / (2 + 8 + 0 + 0 + 1 + 6 + 3 + 1).

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28001598 and 28001607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28001621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 666685 + ... + 666726.

It is an arithmetic number, because the mean of its divisors is an integer number (5333648).

Almost surely, 2^28001631 is an apocalyptic number.

28001631 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

28001631 is a deficient number, since it is larger than the sum of its proper divisors (14667553).

28001631 is a wasteful number, since it uses less digits than its factorization.

28001631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333421.

The product of its (nonzero) digits is 288, while the sum is 21.

The square root of 28001631 is about 5291.6567348988. The cubic root of 28001631 is about 303.6647931167.

The spelling of 28001631 in words is "twenty-eight million, one thousand, six hundred thirty-one".