28121690 has 8 divisors (see below), whose sum is σ = 50619060. Its totient is φ = 11248672.

The previous prime is 28121657. The next prime is 28121707. The reversal of 28121690 is 9612182.

It can be written as a sum of positive squares in 2 ways, for example, as 25532809 + 2588881 = 5053^2 + 1609^2 .

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

It is a super-2 number, since 2×28121690² = 1581658896912200, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1406075 + ... + 1406094.

Almost surely, 2^28121690 is an apocalyptic number.

28121690 is a deficient number, since it is larger than the sum of its proper divisors (22497370).

28121690 is a wasteful number, since it uses less digits than its factorization.

28121690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2812176.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 28121690 is about 5302.9887799240. The cubic root of 28121690 is about 304.0981691840.

The spelling of 28121690 in words is "twenty-eight million, one hundred twenty-one thousand, six hundred ninety".