1981009440 has 96 divisors (see below), whose sum is σ = 6933548160. Its totient is φ = 528268032.

The previous prime is 1981009421. The next prime is 1981009487. The reversal of 1981009440 is 449001891.

It is a tau number, because it is divible by the number of its divisors (96).

It is a super-2 number, since 2×1981009440² = 7848796802738227200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 1981009395 and 1981009404.

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, 224964 + ... + 233603.

It is an arithmetic number, because the mean of its divisors is an integer number (72224460).

Almost surely, 2^1981009440 is an apocalyptic number.

1981009440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1981009440 is an abundant number, since it is smaller than the sum of its proper divisors (4952538720).

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

1981009440 is a wasteful number, since it uses less digits than its factorization.

1981009440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 458591 (or 458577 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 1981009440 is about 44508.5322157449. The cubic root of 1981009440 is about 1255.9205935167.

The spelling of 1981009440 in words is "one billion, nine hundred eighty-one million, nine thousand, four hundred forty".