1581636864 has 108 divisors (see below), whose sum is σ = 4351659648. Its totient is φ = 509967360.

The previous prime is 1581636863. The next prime is 1581636877. The reversal of 1581636864 is 4686361851.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1581636863) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 736977 + ... + 739119.

Almost surely, 2^1581636864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1581636864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2175829824).

1581636864 is an abundant number, since it is smaller than the sum of its proper divisors (2770022784).

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

1581636864 is an equidigital number, since it uses as much as digits as its factorization.

1581636864 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2224 (or 2179 counting only the distinct ones).

The product of its digits is 829440, while the sum is 48.

The square root of 1581636864 is about 39769.7983902358. The cubic root of 1581636864 is about 1165.1153560857.

The spelling of 1581636864 in words is "one billion, five hundred eighty-one million, six hundred thirty-six thousand, eight hundred sixty-four".