256491812500 has 336 divisors, whose sum is σ = 705590968320. Its totient is φ = 79254000000.

The previous prime is 256491812491. The next prime is 256491812557. The reversal of 256491812500 is 5218194652.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 111 ways as a sum of consecutive naturals, for example, 1073187381 + ... + 1073187619.

It is an arithmetic number, because the mean of its divisors is an integer number (2099973120).

Almost surely, 2^256491812500 is an apocalyptic number.

256491812500 is a gapful number since it is divisible by the number (20) 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 256491812500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (352795484160).

256491812500 is an abundant number, since it is smaller than the sum of its proper divisors (449099155820).

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

256491812500 is a wasteful number, since it uses less digits than its factorization.

256491812500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514 (or 487 counting only the distinct ones).

The product of its (nonzero) digits is 172800, while the sum is 43.

The spelling of 256491812500 in words is "two hundred fifty-six billion, four hundred ninety-one million, eight hundred twelve thousand, five hundred".