661015618 has 32 divisors (see below), whose sum is σ = 1042418160. Its totient is φ = 313958400.

The previous prime is 661015603. The next prime is 661015633. The reversal of 661015618 is 816510166.

It is an interprime number because it is at equal distance from previous prime (661015603) and next prime (661015633).

It can be written as a sum of positive squares in 8 ways, for example, as 639735849 + 21279769 = 25293^2 + 4613^2 .

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 1648218 + ... + 1648618.

Almost surely, 2^661015618 is an apocalyptic number.

661015618 is a deficient number, since it is larger than the sum of its proper divisors (381402542).

661015618 is a wasteful number, since it uses less digits than its factorization.

661015618 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 822.

The product of its (nonzero) digits is 8640, while the sum is 34.

The square root of 661015618 is about 25710.2239974684. The cubic root of 661015618 is about 871.1051345395.

The spelling of 661015618 in words is "six hundred sixty-one million, fifteen thousand, six hundred eighteen".