2166721542 has 16 divisors (see below), whose sum is σ = 4814936880. Its totient is φ = 722240496.

The previous prime is 2166721537. The next prime is 2166721577. The reversal of 2166721542 is 2451276612.

It is a happy number.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 2166721497 and 2166721506.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 20062183 + ... + 20062290.

It is an arithmetic number, because the mean of its divisors is an integer number (300933555).

Almost surely, 2^2166721542 is an apocalyptic number.

2166721542 is an abundant number, since it is smaller than the sum of its proper divisors (2648215338).

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

2166721542 is a wasteful number, since it uses less digits than its factorization.

2166721542 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40124484 (or 40124478 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 2166721542 is about 46548.0562644672. The cubic root of 2166721542 is about 1294.0002703397. Note that the first 3 decimals are identical.

The spelling of 2166721542 in words is "two billion, one hundred sixty-six million, seven hundred twenty-one thousand, five hundred forty-two".