661635677501 has 12 divisors (see below), whose sum is σ = 713964585600. Its totient is φ = 612453767640.

The previous prime is 661635677471. The next prime is 661635677569. The reversal of 661635677501 is 105776536166.

It is not a de Polignac number, because 661635677501 - 2¹⁴ = 661635661117 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (661635674501) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20156651 + ... + 20189448.

It is an arithmetic number, because the mean of its divisors is an integer number (59497048800).

Almost surely, 2^661635677501 is an apocalyptic number.

It is an amenable number.

661635677501 is a deficient number, since it is larger than the sum of its proper divisors (52328908099).

661635677501 is a wasteful number, since it uses less digits than its factorization.

661635677501 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40346176 (or 40346153 counting only the distinct ones).

The product of its (nonzero) digits is 4762800, while the sum is 53.

The spelling of 661635677501 in words is "six hundred sixty-one billion, six hundred thirty-five million, six hundred seventy-seven thousand, five hundred one".