1321978417 has 4 divisors (see below), whose sum is σ = 1346921460. Its totient is φ = 1297035376.

The previous prime is 1321978393. The next prime is 1321978451. The reversal of 1321978417 is 7148791231.

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

It can be written as a sum of positive squares in 2 ways, for example, as 312264241 + 1009714176 = 17671^2 + 31776^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1321978417 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1321978517) 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, 12471442 + ... + 12471547.

It is an arithmetic number, because the mean of its divisors is an integer number (336730365).

Almost surely, 2^1321978417 is an apocalyptic number.

It is an amenable number.

1321978417 is a deficient number, since it is larger than the sum of its proper divisors (24943043).

1321978417 is an equidigital number, since it uses as much as digits as its factorization.

1321978417 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24943042.

The product of its digits is 84672, while the sum is 43.

The square root of 1321978417 is about 36359.0211226870. The cubic root of 1321978417 is about 1097.5090790600.

The spelling of 1321978417 in words is "one billion, three hundred twenty-one million, nine hundred seventy-eight thousand, four hundred seventeen".