19821357 has 18 divisors (see below), whose sum is σ = 29282318. Its totient is φ = 12920112.

The previous prime is 19821353. The next prime is 19821359. The reversal of 19821357 is 75312891.

It can be written as a sum of positive squares in only one way, i.e., 19105641 + 715716 = 4371^2 + 846^2 .

It is not a de Polignac number, because 19821357 - 2² = 19821353 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19821353) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 19383 + ... + 20379.

Almost surely, 2^19821357 is an apocalyptic number.

It is an amenable number.

19821357 is a deficient number, since it is larger than the sum of its proper divisors (9460961).

19821357 is an equidigital number, since it uses as much as digits as its factorization.

19821357 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1097 (or 1047 counting only the distinct ones).

The product of its digits is 15120, while the sum is 36.

The square root of 19821357 is about 4452.1182598848. The cubic root of 19821357 is about 270.6311571900.

The spelling of 19821357 in words is "nineteen million, eight hundred twenty-one thousand, three hundred fifty-seven".