20511431636505 has 32 divisors (see below), whose sum is σ = 33438068296704. Its totient is φ = 10732844618496.

The previous prime is 20511431636483. The next prime is 20511431636539. The reversal of 20511431636505 is 50563613411502.

It is a happy number.

It is not a de Polignac number, because 20511431636505 - 2⁵ = 20511431636473 is a prime.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 56013667 + ... + 56378663.

It is an arithmetic number, because the mean of its divisors is an integer number (1044939634272).

Almost surely, 2^{20511431636505} is an apocalyptic number.

It is an amenable number.

20511431636505 is a deficient number, since it is larger than the sum of its proper divisors (12926636660199).

20511431636505 is a wasteful number, since it uses less digits than its factorization.

20511431636505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 435745.

The product of its (nonzero) digits is 324000, while the sum is 42.

The spelling of 20511431636505 in words is "twenty trillion, five hundred eleven billion, four hundred thirty-one million, six hundred thirty-six thousand, five hundred five".