20664561043515 has 32 divisors (see below), whose sum is σ = 34511099337216. Its totient is φ = 10538783861760.

The previous prime is 20664561043501. The next prime is 20664561043519. The reversal of 20664561043515 is 51534016546602.

It is a happy number.

It is not a de Polignac number, because 20664561043515 - 2²⁵ = 20664527489083 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20664561043519) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7751089 + ... + 10070178.

It is an arithmetic number, because the mean of its divisors is an integer number (1078471854288).

Almost surely, 2^{20664561043515} is an apocalyptic number.

20664561043515 is a deficient number, since it is larger than the sum of its proper divisors (13846538293701).

20664561043515 is a wasteful number, since it uses less digits than its factorization.

20664561043515 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17824659.

The product of its (nonzero) digits is 2592000, while the sum is 48.

The spelling of 20664561043515 in words is "twenty trillion, six hundred sixty-four billion, five hundred sixty-one million, forty-three thousand, five hundred fifteen".