1581564240 has 120 divisors (see below), whose sum is σ = 5349970080. Its totient is φ = 418689792.

The previous prime is 1581564221. The next prime is 1581564287. The reversal of 1581564240 is 424651851.

It is a happy number.

1581564240 is a `hidden beast` number, since 1 + 5 + 8 + 1 + 5 + 642 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

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 = 1581564195 and 1581564204.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 92179 + ... + 107981.

It is an arithmetic number, because the mean of its divisors is an integer number (44583084).

Almost surely, 2^1581564240 is an apocalyptic number.

1581564240 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 1581564240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2674985040).

1581564240 is an abundant number, since it is smaller than the sum of its proper divisors (3768405840).

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

1581564240 is a wasteful number, since it uses less digits than its factorization.

1581564240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15961 (or 15952 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 36.

The square root of 1581564240 is about 39768.8853250880. The cubic root of 1581564240 is about 1165.0975229504.

The spelling of 1581564240 in words is "one billion, five hundred eighty-one million, five hundred sixty-four thousand, two hundred forty".