1981257 has 8 divisors (see below), whose sum is σ = 2681376. Its totient is φ = 1300992.

The previous prime is 1981247. The next prime is 1981267. The reversal of 1981257 is 7521891.

It is an interprime number because it is at equal distance from previous prime (1981247) and next prime (1981267).

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1981257 - 2¹⁰ = 1980233 is a prime.

It is a super-3 number, since 3×1981257³ = 23331555647631544779, which contains 333 as substring.

It is not an unprimeable number, because it can be changed into a prime (1981237) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4728 + ... + 5129.

It is an arithmetic number, because the mean of its divisors is an integer number (335172).

2^1981257 is an apocalyptic number.

It is an amenable number.

1981257 is a deficient number, since it is larger than the sum of its proper divisors (700119).

1981257 is an equidigital number, since it uses as much as digits as its factorization.

1981257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9927.

The product of its digits is 5040, while the sum is 33.

The square root of 1981257 is about 1407.5713125806. The cubic root of 1981257 is about 125.5972907377.

The spelling of 1981257 in words is "one million, nine hundred eighty-one thousand, two hundred fifty-seven".