2181904994 has 4 divisors (see below), whose sum is σ = 3272857494. Its totient is φ = 1090952496.

The previous prime is 2181904981. The next prime is 2181905003. The reversal of 2181904994 is 4994091812.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 1655431969 + 526473025 = 40687^2 + 22945^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 545476247 + ... + 545476250.

Almost surely, 2^2181904994 is an apocalyptic number.

2181904994 is a deficient number, since it is larger than the sum of its proper divisors (1090952500).

2181904994 is a wasteful number, since it uses less digits than its factorization.

2181904994 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1090952499.

The product of its (nonzero) digits is 186624, while the sum is 47.

The square root of 2181904994 is about 46710.8659093363. The cubic root of 2181904994 is about 1297.0158363248.

The spelling of 2181904994 in words is "two billion, one hundred eighty-one million, nine hundred four thousand, nine hundred ninety-four".