28712691 has 32 divisors (see below), whose sum is σ = 49758720. Its totient is φ = 16021152.

The previous prime is 28712689. The next prime is 28712699. The reversal of 28712691 is 19621782.

It is not a de Polignac number, because 28712691 - 2¹ = 28712689 is a prime.

It is a super-2 number, since 2×28712691² = 1648837248922962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (28712699) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 6361 + ... + 9893.

It is an arithmetic number, because the mean of its divisors is an integer number (1554960).

Almost surely, 2^28712691 is an apocalyptic number.

28712691 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

28712691 is a deficient number, since it is larger than the sum of its proper divisors (21046029).

28712691 is a wasteful number, since it uses less digits than its factorization.

28712691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3592 (or 3586 counting only the distinct ones).

The product of its digits is 12096, while the sum is 36.

The square root of 28712691 is about 5358.4224357548. The cubic root of 28712691 is about 306.2137107632.

Subtracting from 28712691 its reverse (19621782), we obtain a palindrome (9090909).

It can be divided in two parts, 28712 and 691, that added together give a triangular number (29403 = T₂₄₂).

The spelling of 28712691 in words is "twenty-eight million, seven hundred twelve thousand, six hundred ninety-one".