6506661601556 has 6 divisors (see below), whose sum is σ = 11386657802730. Its totient is φ = 3253330800776.

The previous prime is 6506661601543. The next prime is 6506661601567. The reversal of 6506661601556 is 6551061666056.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 5236271124100 + 1270390477456 = 2288290^2 + 1127116^2 .

It is a super-2 number, since 2×6506661601556² (a number of 26 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 6506661601498 and 6506661601507.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 813332700191 + ... + 813332700198.

It is an arithmetic number, because the mean of its divisors is an integer number (1897776300455).

Almost surely, 2^{6506661601556} is an apocalyptic number.

It is an amenable number.

6506661601556 is a deficient number, since it is larger than the sum of its proper divisors (4879996201174).

6506661601556 is a wasteful number, since it uses less digits than its factorization.

6506661601556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1626665400393 (or 1626665400391 counting only the distinct ones).

The product of its (nonzero) digits is 5832000, while the sum is 53.

The spelling of 6506661601556 in words is "six trillion, five hundred six billion, six hundred sixty-one million, six hundred one thousand, five hundred fifty-six".