1221681659 has 8 divisors (see below), whose sum is σ = 1411140528. Its totient is φ = 1045288960.

The previous prime is 1221681619. The next prime is 1221681679. The reversal of 1221681659 is 9561861221.

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 1221681659 - 2¹² = 1221677563 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1221681619) 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, 3266342 + ... + 3266715.

It is an arithmetic number, because the mean of its divisors is an integer number (176392566).

Almost surely, 2^1221681659 is an apocalyptic number.

1221681659 is a deficient number, since it is larger than the sum of its proper divisors (189458869).

1221681659 is a wasteful number, since it uses less digits than its factorization.

1221681659 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6533085.

The product of its digits is 51840, while the sum is 41.

The square root of 1221681659 is about 34952.5629818473. The cubic root of 1221681659 is about 1069.0204617464.

The spelling of 1221681659 in words is "one billion, two hundred twenty-one million, six hundred eighty-one thousand, six hundred fifty-nine".