1321998691 has 8 divisors (see below), whose sum is σ = 1424302544. Its totient is φ = 1219782240.

The previous prime is 1321998653. The next prime is 1321998707. The reversal of 1321998691 is 1968991231.

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 1321998691 - 2²⁷ = 1187780963 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1321938691) 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, 11461 + ... + 52681.

It is an arithmetic number, because the mean of its divisors is an integer number (178037818).

Almost surely, 2^1321998691 is an apocalyptic number.

1321998691 is a deficient number, since it is larger than the sum of its proper divisors (102303853).

1321998691 is a wasteful number, since it uses less digits than its factorization.

1321998691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43701.

The product of its digits is 209952, while the sum is 49.

The square root of 1321998691 is about 36359.2999245035. The cubic root of 1321998691 is about 1097.5146895362.

The spelling of 1321998691 in words is "one billion, three hundred twenty-one million, nine hundred ninety-eight thousand, six hundred ninety-one".