819972 has 18 divisors (see below), whose sum is σ = 2072798. Its totient is φ = 273312.

The previous prime is 819943. The next prime is 819977. The reversal of 819972 is 279918.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 799236 + 20736 = 894^2 + 144^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Harshad number since it is a multiple of its sum of digits (36), and also a Moran number because the ratio is a prime number: 22777 = 819972 / (8 + 1 + 9 + 9 + 7 + 2).

It is not an unprimeable number, because it can be changed into a prime (819977) 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, 11353 + ... + 11424.

2⁸¹⁹⁹⁷² is an apocalyptic number.

It is an amenable number.

819972 is an abundant number, since it is smaller than the sum of its proper divisors (1252826).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

819972 is a wasteful number, since it uses less digits than its factorization.

819972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22787 (or 22782 counting only the distinct ones).

The product of its digits is 9072, while the sum is 36.

The square root of 819972 is about 905.5230532681. The cubic root of 819972 is about 93.5979508646.

The spelling of 819972 in words is "eight hundred nineteen thousand, nine hundred seventy-two".