28991890 has 32 divisors (see below), whose sum is σ = 53830656. Its totient is φ = 11235840.

The previous prime is 28991873. The next prime is 28991923. The reversal of 28991890 is 9819982.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 28991890.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 81954 + ... + 82306.

It is an arithmetic number, because the mean of its divisors is an integer number (1682208).

Almost surely, 2^28991890 is an apocalyptic number.

28991890 is a deficient number, since it is larger than the sum of its proper divisors (24838766).

28991890 is a wasteful number, since it uses less digits than its factorization.

28991890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 594.

The product of its (nonzero) digits is 93312, while the sum is 46.

The square root of 28991890 is about 5384.4117598861. The cubic root of 28991890 is about 307.2030402554.

The spelling of 28991890 in words is "twenty-eight million, nine hundred ninety-one thousand, eight hundred ninety".