1221201987 has 32 divisors (see below), whose sum is σ = 1783296000. Its totient is φ = 740333568.

The previous prime is 1221201979. The next prime is 1221202007. The reversal of 1221201987 is 7891021221.

It is not a de Polignac number, because 1221201987 - 2³ = 1221201979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1221201937) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 186139 + ... + 192587.

It is an arithmetic number, because the mean of its divisors is an integer number (55728000).

Almost surely, 2^1221201987 is an apocalyptic number.

1221201987 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

1221201987 is a deficient number, since it is larger than the sum of its proper divisors (562094013).

1221201987 is a wasteful number, since it uses less digits than its factorization.

1221201987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6595.

The product of its (nonzero) digits is 4032, while the sum is 33.

The square root of 1221201987 is about 34945.7005509977. The cubic root of 1221201987 is about 1068.8805326836.

The spelling of 1221201987 in words is "one billion, two hundred twenty-one million, two hundred one thousand, nine hundred eighty-seven".