1331221987 has 2 divisors, whose sum is σ = 1331221988. Its totient is φ = 1331221986.

The previous prime is 1331221949. The next prime is 1331222021. The reversal of 1331221987 is 7891221331.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1331221987 is a prime.

It is not a weakly prime, because it can be changed into another prime (1331821987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 665610993 + 665610994.

It is an arithmetic number, because the mean of its divisors is an integer number (665610994).

Almost surely, 2^1331221987 is an apocalyptic number.

1331221987 is a deficient number, since it is larger than the sum of its proper divisors (1).

1331221987 is an equidigital number, since it uses as much as digits as its factorization.

1331221987 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 37.

The square root of 1331221987 is about 36485.9149124700. The cubic root of 1331221987 is about 1100.0611500441.

The spelling of 1331221987 in words is "one billion, three hundred thirty-one million, two hundred twenty-one thousand, nine hundred eighty-seven".