1251989 has 4 divisors (see below), whose sum is σ = 1256556. Its totient is φ = 1247424.

The previous prime is 1251983. The next prime is 1252021. The reversal of 1251989 is 9891521.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9891521 = 379 ⋅26099.

It can be written as a sum of positive squares in 2 ways, for example, as 819025 + 432964 = 905^2 + 658^2 .

It is a cyclic number.

It is not a de Polignac number, because 1251989 - 2¹² = 1247893 is a prime.

It is a super-2 number, since 2×1251989² = 3134952912242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1251983) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1844 + ... + 2429.

It is an arithmetic number, because the mean of its divisors is an integer number (314139).

2^1251989 is an apocalyptic number.

It is an amenable number.

1251989 is a deficient number, since it is larger than the sum of its proper divisors (4567).

1251989 is an equidigital number, since it uses as much as digits as its factorization.

1251989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4566.

The product of its digits is 6480, while the sum is 35.

The square root of 1251989 is about 1118.9231430264. The cubic root of 1251989 is about 107.7788398316.

The spelling of 1251989 in words is "one million, two hundred fifty-one thousand, nine hundred eighty-nine".