1977198728 has 36 divisors (see below), whose sum is σ = 3773731815. Its totient is φ = 971180496.

The previous prime is 1977198721. The next prime is 1977198731. The reversal of 1977198728 is 8278917791.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in only one way, i.e., 988599364 + 988599364 = 31442^2 + 31442^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=31442.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1977198721) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 9935573 + ... + 9935771.

Almost surely, 2^1977198728 is an apocalyptic number.

It is an amenable number.

1977198728 is a deficient number, since it is larger than the sum of its proper divisors (1796533087).

1977198728 is an frugal number, since it uses more digits than its factorization.

1977198728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 280 counting only the distinct ones).

The product of its digits is 3556224, while the sum is 59.

The square root of 1977198728 is about 44465.7028281349. The cubic root of 1977198728 is about 1255.1147713855.

The spelling of 1977198728 in words is "one billion, nine hundred seventy-seven million, one hundred ninety-eight thousand, seven hundred twenty-eight".