2121217945 has 16 divisors (see below), whose sum is σ = 3173563008. Its totient is φ = 1322317440.

The previous prime is 2121217937. The next prime is 2121217957. The reversal of 2121217945 is 5497121212.

It is not a de Polignac number, because 2121217945 - 2³ = 2121217937 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 2121217945.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2754444 + ... + 2755213.

It is an arithmetic number, because the mean of its divisors is an integer number (198347688).

Almost surely, 2^2121217945 is an apocalyptic number.

It is an amenable number.

2121217945 is a deficient number, since it is larger than the sum of its proper divisors (1052345063).

2121217945 is a wasteful number, since it uses less digits than its factorization.

2121217945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5509680.

The product of its digits is 10080, while the sum is 34.

The square root of 2121217945 is about 46056.6818713637. The cubic root of 2121217945 is about 1284.8776185892.

The spelling of 2121217945 in words is "two billion, one hundred twenty-one million, two hundred seventeen thousand, nine hundred forty-five".