661953501 has 48 divisors (see below), whose sum is σ = 1104929280. Its totient is φ = 377926560.

The previous prime is 661953491. The next prime is 661953527. The reversal of 661953501 is 105359166.

661953501 is a `hidden beast` number, since 6 + 61 + 95 + 3 + 501 = 666.

It is not a de Polignac number, because 661953501 - 2⁶ = 661953437 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661953581) 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 in 47 ways as a sum of consecutive naturals, for example, 150390 + ... + 154728.

It is an arithmetic number, because the mean of its divisors is an integer number (23019360).

Almost surely, 2^661953501 is an apocalyptic number.

It is an amenable number.

661953501 is a deficient number, since it is larger than the sum of its proper divisors (442975779).

661953501 is a wasteful number, since it uses less digits than its factorization.

661953501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4446 (or 4443 counting only the distinct ones).

The product of its (nonzero) digits is 24300, while the sum is 36.

The square root of 661953501 is about 25728.4570271907. The cubic root of 661953501 is about 871.5169294507.

It can be divided in two parts, 66195 and 3501, that added together give a palindrome (69696).

The spelling of 661953501 in words is "six hundred sixty-one million, nine hundred fifty-three thousand, five hundred one".