2157947 has 4 divisors (see below), whose sum is σ = 2354136. Its totient is φ = 1961760.

The previous prime is 2157923. The next prime is 2157989. The reversal of 2157947 is 7497512.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2157947 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (2157907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98078 + ... + 98099.

It is an arithmetic number, because the mean of its divisors is an integer number (588534).

2^2157947 is an apocalyptic number.

2157947 is a deficient number, since it is larger than the sum of its proper divisors (196189).

2157947 is a wasteful number, since it uses less digits than its factorization.

2157947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 196188.

The product of its digits is 17640, while the sum is 35.

The square root of 2157947 is about 1468.9952348459. The cubic root of 2157947 is about 129.2251142123.

The spelling of 2157947 in words is "two million, one hundred fifty-seven thousand, nine hundred forty-seven".