1963221991 has 8 divisors (see below), whose sum is σ = 2020556160. Its totient is φ = 1906689912.

The previous prime is 1963221977. The next prime is 1963222013. The reversal of 1963221991 is 1991223691.

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

It is a cyclic number.

It is not a de Polignac number, because 1963221991 - 2⁹ = 1963221479 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1963221391) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 195555 + ... + 205348.

It is an arithmetic number, because the mean of its divisors is an integer number (252569520).

Almost surely, 2^1963221991 is an apocalyptic number.

1963221991 is a deficient number, since it is larger than the sum of its proper divisors (57334169).

1963221991 is an equidigital number, since it uses as much as digits as its factorization.

1963221991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 401045.

The product of its digits is 52488, while the sum is 43.

The square root of 1963221991 is about 44308.2609791899. The cubic root of 1963221991 is about 1252.1503235126.

The spelling of 1963221991 in words is "one billion, nine hundred sixty-three million, two hundred twenty-one thousand, nine hundred ninety-one".