20661388455 has 8 divisors (see below), whose sum is σ = 33058221552. Its totient is φ = 11019407168.

The previous prime is 20661388439. The next prime is 20661388469. The reversal of 20661388455 is 55488316602.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 20661388455 - 2⁴ = 20661388439 is a prime.

It is a congruent number.

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, 688712934 + ... + 688712963.

It is an arithmetic number, because the mean of its divisors is an integer number (4132277694).

Almost surely, 2^20661388455 is an apocalyptic number.

20661388455 is a deficient number, since it is larger than the sum of its proper divisors (12396833097).

20661388455 is a wasteful number, since it uses less digits than its factorization.

20661388455 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1377425905.

The product of its (nonzero) digits is 1382400, while the sum is 48.

The spelling of 20661388455 in words is "twenty billion, six hundred sixty-one million, three hundred eighty-eight thousand, four hundred fifty-five".