28991700 has 54 divisors (see below), whose sum is σ = 90875694. Its totient is φ = 7730880.

The previous prime is 28991659. The next prime is 28991723. The reversal of 28991700 is 719982.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 7033104 + 21958596 = 2652^2 + 4686^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 15207 + ... + 17006.

Almost surely, 2^28991700 is an apocalyptic number.

28991700 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

28991700 is an abundant number, since it is smaller than the sum of its proper divisors (61883994).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

28991700 is a wasteful number, since it uses less digits than its factorization.

28991700 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32233 (or 32223 counting only the distinct ones).

The product of its (nonzero) digits is 9072, while the sum is 36.

The square root of 28991700 is about 5384.3941163329. The cubic root of 28991700 is about 307.2023691630.

The spelling of 28991700 in words is "twenty-eight million, nine hundred ninety-one thousand, seven hundred".