28515081691 has 4 divisors (see below), whose sum is σ = 29498360400. Its totient is φ = 27531802984.

The previous prime is 28515081689. The next prime is 28515081713. The reversal of 28515081691 is 19618051582.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28515081691 - 2¹ = 28515081689 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28515081601) 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, 491639311 + ... + 491639368.

It is an arithmetic number, because the mean of its divisors is an integer number (7374590100).

Almost surely, 2^28515081691 is an apocalyptic number.

28515081691 is a deficient number, since it is larger than the sum of its proper divisors (983278709).

28515081691 is an equidigital number, since it uses as much as digits as its factorization.

28515081691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 983278708.

The product of its (nonzero) digits is 172800, while the sum is 46.

The spelling of 28515081691 in words is "twenty-eight billion, five hundred fifteen million, eighty-one thousand, six hundred ninety-one".