1221111987 has 8 divisors (see below), whose sum is σ = 1629115536. Its totient is φ = 813591552.

The previous prime is 1221111977. The next prime is 1221112001. The reversal of 1221111987 is 7891111221.

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

It is not a de Polignac number, because 1221111987 - 2⁶ = 1221111923 is a prime.

It is a super-2 number, since 2×1221111987² = 2982228969590176338, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (1221111977) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 114838 + ... + 125019.

It is an arithmetic number, because the mean of its divisors is an integer number (203639442).

Almost surely, 2^1221111987 is an apocalyptic number.

1221111987 is a deficient number, since it is larger than the sum of its proper divisors (408003549).

1221111987 is a wasteful number, since it uses less digits than its factorization.

1221111987 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 241557.

The product of its digits is 2016, while the sum is 33.

The square root of 1221111987 is about 34944.4128152127. The cubic root of 1221111987 is about 1068.8542739613.

The spelling of 1221111987 in words is "one billion, two hundred twenty-one million, one hundred eleven thousand, nine hundred eighty-seven".