1221857187 has 8 divisors (see below), whose sum is σ = 1714887360. Its totient is φ = 771699240.

The previous prime is 1221857183. The next prime is 1221857239. The reversal of 1221857187 is 7817581221.

It is a happy number.

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

It is not a de Polignac number, because 1221857187 - 2² = 1221857183 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221857183) 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, 10717989 + ... + 10718102.

It is an arithmetic number, because the mean of its divisors is an integer number (214360920).

Almost surely, 2^1221857187 is an apocalyptic number.

1221857187 is a deficient number, since it is larger than the sum of its proper divisors (493030173).

1221857187 is a wasteful number, since it uses less digits than its factorization.

1221857187 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21436113.

The product of its digits is 62720, while the sum is 42.

The square root of 1221857187 is about 34955.0738377135. The cubic root of 1221857187 is about 1069.0716573085.

The spelling of 1221857187 in words is "one billion, two hundred twenty-one million, eight hundred fifty-seven thousand, one hundred eighty-seven".