2161850781 has 8 divisors (see below), whose sum is σ = 3052024704. Its totient is φ = 1356455360.

The previous prime is 2161850771. The next prime is 2161850807. The reversal of 2161850781 is 1870581612.

2161850781 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 2161850781 - 2¹⁰ = 2161849757 is a prime.

It is a super-2 number, since 2×2161850781² = 9347197598620619922, which contains 22 as substring.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2161850711) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21194565 + ... + 21194666.

It is an arithmetic number, because the mean of its divisors is an integer number (381503088).

Almost surely, 2^2161850781 is an apocalyptic number.

It is an amenable number.

2161850781 is a deficient number, since it is larger than the sum of its proper divisors (890173923).

2161850781 is a wasteful number, since it uses less digits than its factorization.

2161850781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 42389251.

The product of its (nonzero) digits is 26880, while the sum is 39.

The square root of 2161850781 is about 46495.7071244217. The cubic root of 2161850781 is about 1293.0299111003.

The spelling of 2161850781 in words is "two billion, one hundred sixty-one million, eight hundred fifty thousand, seven hundred eighty-one".