1251581 has 2 divisors, whose sum is σ = 1251582. Its totient is φ = 1251580.

The previous prime is 1251577. The next prime is 1251583. The reversal of 1251581 is 1851521.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 931225 + 320356 = 965^2 + 566^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251581 - 2² = 1251577 is a prime.

It is a super-2 number, since 2×1251581² = 3132909999122, which contains 22 as substring.

Together with 1251583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1251583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 625790 + 625791.

It is an arithmetic number, because the mean of its divisors is an integer number (625791).

2^1251581 is an apocalyptic number.

It is an amenable number.

1251581 is a deficient number, since it is larger than the sum of its proper divisors (1).

1251581 is an equidigital number, since it uses as much as digits as its factorization.

1251581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 400, while the sum is 23.

The square root of 1251581 is about 1118.7408100181. The cubic root of 1251581 is about 107.7671308511.

The spelling of 1251581 in words is "one million, two hundred fifty-one thousand, five hundred eighty-one".