661653637 has 4 divisors (see below), whose sum is σ = 661738336. Its totient is φ = 661568940.

The previous prime is 661653611. The next prime is 661653659. The reversal of 661653637 is 736356166.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 661653637 - 2¹¹ = 661651589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661653593 and 661653602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661653697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29289 + ... + 46702.

It is an arithmetic number, because the mean of its divisors is an integer number (165434584).

Almost surely, 2^661653637 is an apocalyptic number.

It is an amenable number.

661653637 is a deficient number, since it is larger than the sum of its proper divisors (84699).

661653637 is an equidigital number, since it uses as much as digits as its factorization.

661653637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84698.

The product of its digits is 408240, while the sum is 43.

The square root of 661653637 is about 25722.6288897539. The cubic root of 661653637 is about 871.3853109288.

The spelling of 661653637 in words is "six hundred sixty-one million, six hundred fifty-three thousand, six hundred thirty-seven".