661356513416266 has 16 divisors (see below), whose sum is σ = 1026249958133640. Its totient is φ = 319273351649280.

The previous prime is 661356513416239. The next prime is 661356513416309. The reversal of 661356513416266 is 662614315653166.

It can be written as a sum of positive squares in 4 ways, for example, as 660383143722241 + 973369694025 = 25697921^2 + 986595^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30922491 + ... + 47737966.

Almost surely, 2^{661356513416266} is an apocalyptic number.

661356513416266 is a deficient number, since it is larger than the sum of its proper divisors (364893444717374).

661356513416266 is a wasteful number, since it uses less digits than its factorization.

661356513416266 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78805449.

The product of its digits is 83980800, while the sum is 61.

The spelling of 661356513416266 in words is "six hundred sixty-one trillion, three hundred fifty-six billion, five hundred thirteen million, four hundred sixteen thousand, two hundred sixty-six".