2121544978 has 48 divisors (see below), whose sum is σ = 4002304320. Its totient is φ = 823873248.

The previous prime is 2121544963. The next prime is 2121544981. The reversal of 2121544978 is 8794451212.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 133176 + ... + 148252.

It is an arithmetic number, because the mean of its divisors is an integer number (83381340).

Almost surely, 2^2121544978 is an apocalyptic number.

2121544978 is a deficient number, since it is larger than the sum of its proper divisors (1880759342).

2121544978 is a wasteful number, since it uses less digits than its factorization.

2121544978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15151 (or 15128 counting only the distinct ones).

The product of its digits is 161280, while the sum is 43.

The square root of 2121544978 is about 46060.2320662847. The cubic root of 2121544978 is about 1284.9436460320.

The spelling of 2121544978 in words is "two billion, one hundred twenty-one million, five hundred forty-four thousand, nine hundred seventy-eight".