19781973 has 12 divisors (see below), whose sum is σ = 29559660. Its totient is φ = 12733056.

The previous prime is 19781969. The next prime is 19781981. The reversal of 19781973 is 37918791.

It can be written as a sum of positive squares in 2 ways, for example, as 13264164 + 6517809 = 3642^2 + 2553^2 .

It is not a de Polignac number, because 19781973 - 2² = 19781969 is a prime.

It is a hoax number, since the sum of its digits (45) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19781953) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 37636 + ... + 38157.

It is an arithmetic number, because the mean of its divisors is an integer number (2463305).

Almost surely, 2^19781973 is an apocalyptic number.

It is an amenable number.

19781973 is a deficient number, since it is larger than the sum of its proper divisors (9777687).

19781973 is a wasteful number, since it uses less digits than its factorization.

19781973 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 75828 (or 75825 counting only the distinct ones).

The product of its digits is 95256, while the sum is 45.

The square root of 19781973 is about 4447.6929974988. The cubic root of 19781973 is about 270.4517950233.

The spelling of 19781973 in words is "nineteen million, seven hundred eighty-one thousand, nine hundred seventy-three".