1256521002 has 64 divisors (see below), whose sum is σ = 2783963520. Its totient is φ = 374912000.

The previous prime is 1256521001. The next prime is 1256521003. The reversal of 1256521002 is 2001256521.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (1256521001) and next prime (1256521003).

It is not an unprimeable number, because it can be changed into a prime (1256521001) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1552774 + ... + 1553582.

It is an arithmetic number, because the mean of its divisors is an integer number (43499430).

Almost surely, 2^1256521002 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1256521002, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1391981760).

1256521002 is an abundant number, since it is smaller than the sum of its proper divisors (1527442518).

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

1256521002 is a wasteful number, since it uses less digits than its factorization.

1256521002 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1159.

The product of its (nonzero) digits is 1200, while the sum is 24.

The square root of 1256521002 is about 35447.4399921913. The cubic root of 1256521002 is about 1079.0873067591.

Adding to 1256521002 its reverse (2001256521), we get a palindrome (3257777523).

The spelling of 1256521002 in words is "one billion, two hundred fifty-six million, five hundred twenty-one thousand, two".