2161566540 has 192 divisors, whose sum is σ = 8090342400. Its totient is φ = 468052992.

The previous prime is 2161566523. The next prime is 2161566557. The reversal of 2161566540 is 456651612.

2161566540 is a `hidden beast` number, since 2 + 1 + 61 + 56 + 6 + 540 = 666.

It is an interprime number because it is at equal distance from previous prime (2161566523) and next prime (2161566557).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 2161566495 and 2161566504.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 56772 + ... + 86868.

It is an arithmetic number, because the mean of its divisors is an integer number (42137200).

Almost surely, 2^2161566540 is an apocalyptic number.

2161566540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 2161566540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4045171200).

2161566540 is an abundant number, since it is smaller than the sum of its proper divisors (5928775860).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

2161566540 is a wasteful number, since it uses less digits than its factorization.

2161566540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30141 (or 30133 counting only the distinct ones).

The product of its (nonzero) digits is 43200, while the sum is 36.

The square root of 2161566540 is about 46492.6503869160. The cubic root of 2161566540 is about 1292.9732392543.

The spelling of 2161566540 in words is "two billion, one hundred sixty-one million, five hundred sixty-six thousand, five hundred forty".