661491522050 has 18 divisors (see below), whose sum is σ = 1230384928059. Its totient is φ = 264594308400.

The previous prime is 661491522047. The next prime is 661491522079. The reversal of 661491522050 is 50225194166.

It can be written as a sum of positive squares in 5 ways, for example, as 635156399089 + 26335122961 = 796967^2 + 162281^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=575105.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 661491521989 and 661491522007.

It is an unprimeable number.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5693540 + ... + 5808560.

Almost surely, 2^661491522050 is an apocalyptic number.

661491522050 is a deficient number, since it is larger than the sum of its proper divisors (568893406009).

661491522050 is an frugal number, since it uses more digits than its factorization.

661491522050 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230054 (or 115028 counting only the distinct ones).

The product of its (nonzero) digits is 129600, while the sum is 41.

The spelling of 661491522050 in words is "six hundred sixty-one billion, four hundred ninety-one million, five hundred twenty-two thousand, fifty".