1251005521 has 2 divisors, whose sum is σ = 1251005522. Its totient is φ = 1251005520.

The previous prime is 1251005513. The next prime is 1251005531. The reversal of 1251005521 is 1255001521.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1246443025 + 4562496 = 35305^2 + 2136^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251005521 - 2³ = 1251005513 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1251005492 and 1251005501.

It is not a weakly prime, because it can be changed into another prime (1251005501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625502760 + 625502761.

It is an arithmetic number, because the mean of its divisors is an integer number (625502761).

Almost surely, 2^1251005521 is an apocalyptic number.

It is an amenable number.

1251005521 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251005521 is an equidigital number, since it uses as much as digits as its factorization.

1251005521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 500, while the sum is 22.

The square root of 1251005521 is about 35369.5564150867. The cubic root of 1251005521 is about 1077.5061115101.

The spelling of 1251005521 in words is "one billion, two hundred fifty-one million, five thousand, five hundred twenty-one".