256561500 has 192 divisors, whose sum is σ = 821882880. Its totient is φ = 61804800.

The previous prime is 256561453. The next prime is 256561507. The reversal of 256561500 is 5165652.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256561507) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1150389 + ... + 1150611.

It is an arithmetic number, because the mean of its divisors is an integer number (4280640).

Almost surely, 2^256561500 is an apocalyptic number.

256561500 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 256561500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (410941440).

256561500 is an abundant number, since it is smaller than the sum of its proper divisors (565321380).

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

256561500 is a wasteful number, since it uses less digits than its factorization.

256561500 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317 (or 305 counting only the distinct ones).

The product of its (nonzero) digits is 9000, while the sum is 30.

The square root of 256561500 is about 16017.5372638867. The cubic root of 256561500 is about 635.4243139215.

The spelling of 256561500 in words is "two hundred fifty-six million, five hundred sixty-one thousand, five hundred".