20635311056561 has 16 divisors (see below), whose sum is σ = 20968655995968. Its totient is φ = 20304510408000.

The previous prime is 20635311056551. The next prime is 20635311056707. The reversal of 20635311056561 is 16565011353602.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 20635311056561 - 2⁴² = 16237264545457 is a prime.

It is a super-2 number, since 2×20635311056561² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20635311056551) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 581406026 + ... + 581441516.

It is an arithmetic number, because the mean of its divisors is an integer number (1310540999748).

Almost surely, 2^{20635311056561} is an apocalyptic number.

It is an amenable number.

20635311056561 is a deficient number, since it is larger than the sum of its proper divisors (333344939407).

20635311056561 is a wasteful number, since it uses less digits than its factorization.

20635311056561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71072.

The product of its (nonzero) digits is 486000, while the sum is 44.

The spelling of 20635311056561 in words is "twenty trillion, six hundred thirty-five billion, three hundred eleven million, fifty-six thousand, five hundred sixty-one".