1681444440 has 512 divisors, whose sum is σ = 6502809600. Its totient is φ = 383201280.

The previous prime is 1681444439. The next prime is 1681444459. The reversal of 1681444440 is 444441861.

1681444440 is a `hidden beast` number, since 168 + 14 + 44 + 440 = 666.

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 = 1681444395 and 1681444404.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 13239657 + ... + 13239783.

It is an arithmetic number, because the mean of its divisors is an integer number (12700800).

Almost surely, 2^1681444440 is an apocalyptic number.

1681444440 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1681444440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (3251404800).

1681444440 is an abundant number, since it is smaller than the sum of its proper divisors (4821365160).

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

1681444440 is a wasteful number, since it uses less digits than its factorization.

1681444440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 224 (or 214 counting only the distinct ones).

The product of its (nonzero) digits is 49152, while the sum is 36.

The square root of 1681444440 is about 41005.4196417986. The cubic root of 1681444440 is about 1189.1249929017.

The spelling of 1681444440 in words is "one billion, six hundred eighty-one million, four hundred forty-four thousand, four hundred forty".