1993820491 has 4 divisors (see below), whose sum is σ = 2147191312. Its totient is φ = 1840449672.

The previous prime is 1993820489. The next prime is 1993820513. The reversal of 1993820491 is 1940283991.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1940283991 = 1103 ⋅1759097.

It is a cyclic number.

It is not a de Polignac number, because 1993820491 - 2¹ = 1993820489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1993820471) 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, 76685391 + ... + 76685416.

It is an arithmetic number, because the mean of its divisors is an integer number (536797828).

Almost surely, 2^1993820491 is an apocalyptic number.

1993820491 is a deficient number, since it is larger than the sum of its proper divisors (153370821).

1993820491 is a wasteful number, since it uses less digits than its factorization.

1993820491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 153370820.

The product of its (nonzero) digits is 139968, while the sum is 46.

The square root of 1993820491 is about 44652.2170894123. The cubic root of 1993820491 is about 1258.6220955804.

The spelling of 1993820491 in words is "one billion, nine hundred ninety-three million, eight hundred twenty thousand, four hundred ninety-one".