1321921645 has 24 divisors (see below), whose sum is σ = 1792308960. Its totient is φ = 928213440.

The previous prime is 1321921613. The next prime is 1321921691. The reversal of 1321921645 is 5461291231.

It is not a de Polignac number, because 1321921645 - 2⁵ = 1321921613 is a prime.

It is a super-3 number, since 3×1321921645³ (a number of 28 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1321921645.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31966 + ... + 60544.

It is an arithmetic number, because the mean of its divisors is an integer number (74679540).

Almost surely, 2^1321921645 is an apocalyptic number.

It is an amenable number.

1321921645 is a deficient number, since it is larger than the sum of its proper divisors (470387315).

1321921645 is a wasteful number, since it uses less digits than its factorization.

1321921645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28653 (or 28624 counting only the distinct ones).

The product of its digits is 12960, while the sum is 34.

The square root of 1321921645 is about 36358.2404002174. The cubic root of 1321921645 is about 1097.4933680931.

The spelling of 1321921645 in words is "one billion, three hundred twenty-one million, nine hundred twenty-one thousand, six hundred forty-five".