20661266506 has 8 divisors (see below), whose sum is σ = 32814952740. Its totient is φ = 9722948928.

The previous prime is 20661266473. The next prime is 20661266513. The reversal of 20661266506 is 60566216602.

It can be written as a sum of positive squares in 2 ways, for example, as 20613780625 + 47485881 = 143575^2 + 6891^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 303842121 + ... + 303842188.

Almost surely, 2^20661266506 is an apocalyptic number.

20661266506 is a deficient number, since it is larger than the sum of its proper divisors (12153686234).

20661266506 is a wasteful number, since it uses less digits than its factorization.

20661266506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 607684328.

The product of its (nonzero) digits is 155520, while the sum is 40.

The spelling of 20661266506 in words is "twenty billion, six hundred sixty-one million, two hundred sixty-six thousand, five hundred six".