1978509 has 16 divisors (see below), whose sum is σ = 2875712. Its totient is φ = 1202688.

The previous prime is 1978507. The next prime is 1978523. The reversal of 1978509 is 9058791.

It is a happy number.

It is not a de Polignac number, because 1978509 - 2¹ = 1978507 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978507) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3522 + ... + 4044.

It is an arithmetic number, because the mean of its divisors is an integer number (179732).

2^1978509 is an apocalyptic number.

It is an amenable number.

1978509 is a deficient number, since it is larger than the sum of its proper divisors (897203).

1978509 is a wasteful number, since it uses less digits than its factorization.

1978509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 636.

The product of its (nonzero) digits is 22680, while the sum is 39.

The square root of 1978509 is about 1406.5948243897. The cubic root of 1978509 is about 125.5391961294.

The spelling of 1978509 in words is "one million, nine hundred seventy-eight thousand, five hundred nine".