1978157 has 2 divisors, whose sum is σ = 1978158. Its totient is φ = 1978156.

The previous prime is 1978153. The next prime is 1978159. The reversal of 1978157 is 7518791.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1142761 + 835396 = 1069^2 + 914^2 .

It is a cyclic number.

It is not a de Polignac number, because 1978157 - 2² = 1978153 is a prime.

Together with 1978159, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1978157.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1978153) 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 as a sum of consecutive naturals, namely, 989078 + 989079.

It is an arithmetic number, because the mean of its divisors is an integer number (989079).

2^1978157 is an apocalyptic number.

It is an amenable number.

1978157 is a deficient number, since it is larger than the sum of its proper divisors (1).

1978157 is an equidigital number, since it uses as much as digits as its factorization.

1978157 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17640, while the sum is 38.

The square root of 1978157 is about 1406.4696939501. The cubic root of 1978157 is about 125.5317507217.

The spelling of 1978157 in words is "one million, nine hundred seventy-eight thousand, one hundred fifty-seven".