20516051661 has 16 divisors (see below), whose sum is σ = 31264694784. Its totient is φ = 11722655664.

The previous prime is 20516051659. The next prime is 20516051701. The reversal of 20516051661 is 16615061502.

It is not a de Polignac number, because 20516051661 - 2¹ = 20516051659 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20516051261) 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, 430170 + ... + 475476.

It is an arithmetic number, because the mean of its divisors is an integer number (1954043424).

Almost surely, 2^20516051661 is an apocalyptic number.

20516051661 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

20516051661 is a deficient number, since it is larger than the sum of its proper divisors (10748643123).

20516051661 is a wasteful number, since it uses less digits than its factorization.

20516051661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66880.

The product of its (nonzero) digits is 10800, while the sum is 33.

The spelling of 20516051661 in words is "twenty billion, five hundred sixteen million, fifty-one thousand, six hundred sixty-one".