1321955566 has 4 divisors (see below), whose sum is σ = 1982933352. Its totient is φ = 660977782.

The previous prime is 1321955563. The next prime is 1321955617. The reversal of 1321955566 is 6655591231.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1321955563) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330488890 + ... + 330488893.

It is an arithmetic number, because the mean of its divisors is an integer number (495733338).

Almost surely, 2^1321955566 is an apocalyptic number.

1321955566 is a deficient number, since it is larger than the sum of its proper divisors (660977786).

1321955566 is an equidigital number, since it uses as much as digits as its factorization.

1321955566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 660977785.

The product of its digits is 243000, while the sum is 43.

The square root of 1321955566 is about 36358.7068801958. The cubic root of 1321955566 is about 1097.5027553752.

The spelling of 1321955566 in words is "one billion, three hundred twenty-one million, nine hundred fifty-five thousand, five hundred sixty-six".