1221857917 has 8 divisors (see below), whose sum is σ = 1397746112. Its totient is φ = 1046304000.

The previous prime is 1221857873. The next prime is 1221857929. The reversal of 1221857917 is 7197581221.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1221857917 - 2⁷ = 1221857789 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1221857977) 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, 75684 + ... + 90397.

It is an arithmetic number, because the mean of its divisors is an integer number (174718264).

Almost surely, 2^1221857917 is an apocalyptic number.

It is an amenable number.

1221857917 is a deficient number, since it is larger than the sum of its proper divisors (175888195).

1221857917 is a wasteful number, since it uses less digits than its factorization.

1221857917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 167139.

The product of its digits is 70560, while the sum is 43.

The square root of 1221857917 is about 34955.0842796867. The cubic root of 1221857917 is about 1069.0718702145.

The spelling of 1221857917 in words is "one billion, two hundred twenty-one million, eight hundred fifty-seven thousand, nine hundred seventeen".