20405661061 has 16 divisors (see below), whose sum is σ = 21659489280. Its totient is φ = 19190355840.

The previous prime is 20405661043. The next prime is 20405661071. The reversal of 20405661061 is 16016650402.

It is a cyclic number.

It is not a de Polignac number, because 20405661061 - 2⁹ = 20405660549 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20405661011) 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, 972600 + ... + 993358.

It is an arithmetic number, because the mean of its divisors is an integer number (1353718080).

Almost surely, 2^20405661061 is an apocalyptic number.

It is an amenable number.

20405661061 is a deficient number, since it is larger than the sum of its proper divisors (1253828219).

20405661061 is a wasteful number, since it uses less digits than its factorization.

20405661061 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21684.

The product of its (nonzero) digits is 8640, while the sum is 31.

The spelling of 20405661061 in words is "twenty billion, four hundred five million, six hundred sixty-one thousand, sixty-one".