661888305 has 48 divisors (see below), whose sum is σ = 1237856256. Its totient is φ = 325238400.

The previous prime is 661888303. The next prime is 661888321. The reversal of 661888305 is 503888166.

It is not a de Polignac number, because 661888305 - 2¹ = 661888303 is a prime.

It is a super-2 number, since 2×661888305² = 876192256591546050, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (661888303) 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 in 47 ways as a sum of consecutive naturals, for example, 574480 + ... + 575630.

It is an arithmetic number, because the mean of its divisors is an integer number (25788672).

Almost surely, 2^661888305 is an apocalyptic number.

661888305 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

661888305 is a deficient number, since it is larger than the sum of its proper divisors (575967951).

661888305 is a wasteful number, since it uses less digits than its factorization.

661888305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2158 (or 2155 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The square root of 661888305 is about 25727.1899942454. The cubic root of 661888305 is about 871.4883165229.

The spelling of 661888305 in words is "six hundred sixty-one million, eight hundred eighty-eight thousand, three hundred five".