20561212634 has 16 divisors (see below), whose sum is σ = 32470476480. Its totient is φ = 9737900640.

The previous prime is 20561212619. The next prime is 20561212643. The reversal of 20561212634 is 43621216502.

It is a super-2 number, since 2×20561212634² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 20561212634.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 204179 + ... + 287769.

It is an arithmetic number, because the mean of its divisors is an integer number (2029404780).

Almost surely, 2^20561212634 is an apocalyptic number.

20561212634 is a deficient number, since it is larger than the sum of its proper divisors (11909263846).

20561212634 is a wasteful number, since it uses less digits than its factorization.

20561212634 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90085.

The product of its (nonzero) digits is 17280, while the sum is 32.

The spelling of 20561212634 in words is "twenty billion, five hundred sixty-one million, two hundred twelve thousand, six hundred thirty-four".