1981182640 has 20 divisors (see below), whose sum is σ = 4606249824. Its totient is φ = 792473024.

The previous prime is 1981182629. The next prime is 1981182659. The reversal of 1981182640 is 462811891.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 1981182593 and 1981182602.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12382312 + ... + 12382471.

Almost surely, 2^1981182640 is an apocalyptic number.

1981182640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1981182640 is an abundant number, since it is smaller than the sum of its proper divisors (2625067184).

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

1981182640 is a wasteful number, since it uses less digits than its factorization.

1981182640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24764796 (or 24764790 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 40.

The square root of 1981182640 is about 44510.4778675763. The cubic root of 1981182640 is about 1255.9571942354.

The spelling of 1981182640 in words is "one billion, nine hundred eighty-one million, one hundred eighty-two thousand, six hundred forty".