661142987 has 2 divisors, whose sum is σ = 661142988. Its totient is φ = 661142986.

The previous prime is 661142959. The next prime is 661143001. The reversal of 661142987 is 789241166.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661142987 is a prime.

It is a super-2 number, since 2×661142987² = 874220098518564338, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661142687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330571493 + 330571494.

It is an arithmetic number, because the mean of its divisors is an integer number (330571494).

Almost surely, 2^661142987 is an apocalyptic number.

661142987 is a deficient number, since it is larger than the sum of its proper divisors (1).

661142987 is an equidigital number, since it uses as much as digits as its factorization.

661142987 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 145152, while the sum is 44.

The square root of 661142987 is about 25712.7008888604. The cubic root of 661142987 is about 871.1610811069.

The spelling of 661142987 in words is "six hundred sixty-one million, one hundred forty-two thousand, nine hundred eighty-seven".