661042651 has 2 divisors, whose sum is σ = 661042652. Its totient is φ = 661042650.

The previous prime is 661042619. The next prime is 661042663. The reversal of 661042651 is 156240166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661042651 - 2⁵ = 661042619 is a prime.

It is a super-2 number, since 2×661042651² = 873954772882215602, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (661042601) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330521325 + 330521326.

It is an arithmetic number, because the mean of its divisors is an integer number (330521326).

Almost surely, 2^661042651 is an apocalyptic number.

661042651 is a deficient number, since it is larger than the sum of its proper divisors (1).

661042651 is an equidigital number, since it uses as much as digits as its factorization.

661042651 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8640, while the sum is 31.

The square root of 661042651 is about 25710.7497168013. The cubic root of 661042651 is about 871.1170093291.

The spelling of 661042651 in words is "six hundred sixty-one million, forty-two thousand, six hundred fifty-one".