1978042640 has 40 divisors (see below), whose sum is σ = 5255943360. Its totient is φ = 678185856.

The previous prime is 1978042621. The next prime is 1978042657. The reversal of 1978042640 is 462408791.

It is a tau number, because it is divible by the number of its divisors (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1765550 + ... + 1766669.

It is an arithmetic number, because the mean of its divisors is an integer number (131398584).

Almost surely, 2^1978042640 is an apocalyptic number.

1978042640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1978042640 is an abundant number, since it is smaller than the sum of its proper divisors (3277900720).

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

1978042640 is a wasteful number, since it uses less digits than its factorization.

1978042640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3532239 (or 3532233 counting only the distinct ones).

The product of its (nonzero) digits is 96768, while the sum is 41.

The square root of 1978042640 is about 44475.1912868287. The cubic root of 1978042640 is about 1255.2933162024.

The spelling of 1978042640 in words is "one billion, nine hundred seventy-eight million, forty-two thousand, six hundred forty".