1978551 has 6 divisors (see below), whose sum is σ = 2857920. Its totient is φ = 1319028.

The previous prime is 1978541. The next prime is 1978567. The reversal of 1978551 is 1558791.

It is not a de Polignac number, because 1978551 - 2⁷ = 1978423 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1978531) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 109911 + ... + 109928.

It is an arithmetic number, because the mean of its divisors is an integer number (476320).

2^1978551 is an apocalyptic number.

1978551 is a deficient number, since it is larger than the sum of its proper divisors (879369).

1978551 is a wasteful number, since it uses less digits than its factorization.

1978551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219845 (or 219842 counting only the distinct ones).

The product of its digits is 12600, while the sum is 36.

The square root of 1978551 is about 1406.6097539830. The cubic root of 1978551 is about 125.5400844429.

The spelling of 1978551 in words is "one million, nine hundred seventy-eight thousand, five hundred fifty-one".