1321990478 has 4 divisors (see below), whose sum is σ = 1982985720. Its totient is φ = 660995238.

The previous prime is 1321990459. The next prime is 1321990487. The reversal of 1321990478 is 8740991231.

It is a semiprime because it is the product of two primes.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330497618 + ... + 330497621.

It is an arithmetic number, because the mean of its divisors is an integer number (495746430).

Almost surely, 2^1321990478 is an apocalyptic number.

1321990478 is a deficient number, since it is larger than the sum of its proper divisors (660995242).

1321990478 is an equidigital number, since it uses as much as digits as its factorization.

1321990478 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 660995241.

The product of its (nonzero) digits is 108864, while the sum is 44.

The square root of 1321990478 is about 36359.1869821095. The cubic root of 1321990478 is about 1097.5124167385.

The spelling of 1321990478 in words is "one billion, three hundred twenty-one million, nine hundred ninety thousand, four hundred seventy-eight".