1820994978 has 64 divisors (see below), whose sum is σ = 4071555072. Its totient is φ = 538222080.

The previous prime is 1820994977. The next prime is 1820994983. The reversal of 1820994978 is 8794990281.

It is not an unprimeable number, because it can be changed into a prime (1820994977) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1094175 + ... + 1095837.

It is an arithmetic number, because the mean of its divisors is an integer number (63618048).

Almost surely, 2^1820994978 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1820994978, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2035777536).

1820994978 is an abundant number, since it is smaller than the sum of its proper divisors (2250560094).

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

1820994978 is a wasteful number, since it uses less digits than its factorization.

1820994978 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2079.

The product of its (nonzero) digits is 2612736, while the sum is 57.

The square root of 1820994978 is about 42673.1177440786. The cubic root of 1820994978 is about 1221.1515996255.

The spelling of 1820994978 in words is "one billion, eight hundred twenty million, nine hundred ninety-four thousand, nine hundred seventy-eight".