2191690 has 8 divisors (see below), whose sum is σ = 3945060. Its totient is φ = 876672.

The previous prime is 2191687. The next prime is 2191703. The reversal of 2191690 is 961912.

It can be written as a sum of positive squares in 2 ways, for example, as 2152089 + 39601 = 1467^2 + 199^2 .

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

It is a super-2 number, since 2×2191690² = 9607010112200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109575 + ... + 109594.

2^2191690 is an apocalyptic number.

2191690 is a deficient number, since it is larger than the sum of its proper divisors (1753370).

2191690 is a wasteful number, since it uses less digits than its factorization.

2191690 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219176.

The product of its (nonzero) digits is 972, while the sum is 28.

The square root of 2191690 is about 1480.4357466638. The cubic root of 2191690 is about 129.8951817806.

The spelling of 2191690 in words is "two million, one hundred ninety-one thousand, six hundred ninety".