1221406643 has 8 divisors (see below), whose sum is σ = 1229142096. Its totient is φ = 1213682400.

The previous prime is 1221406607. The next prime is 1221406661. The reversal of 1221406643 is 3466041221.

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 1221406643 - 2⁶ = 1221406579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221400643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 348128 + ... + 351618.

It is an arithmetic number, because the mean of its divisors is an integer number (153642762).

Almost surely, 2^1221406643 is an apocalyptic number.

1221406643 is a deficient number, since it is larger than the sum of its proper divisors (7735453).

1221406643 is a wasteful number, since it uses less digits than its factorization.

1221406643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5605.

The product of its (nonzero) digits is 6912, while the sum is 29.

The square root of 1221406643 is about 34948.6286283167. The cubic root of 1221406643 is about 1068.9402390488.

Adding to 1221406643 its reverse (3466041221), we get a palindrome (4687447864).

The spelling of 1221406643 in words is "one billion, two hundred twenty-one million, four hundred six thousand, six hundred forty-three".