19835623921 has 3 divisors (see below), whose sum is σ = 19835764761. Its totient is φ = 19835483082.

The previous prime is 19835623861. The next prime is 19835623939. The reversal of 19835623921 is 12932653891.

The square root of 19835623921 is 140839.

It is a perfect power (a square), and thus also a powerful number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is not a de Polignac number, because 19835623921 - 2¹³ = 19835615729 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19835623961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 70420 + ... + 211258.

It is an arithmetic number, because the mean of its divisors is an integer number (6611921587).

Almost surely, 2^19835623921 is an apocalyptic number.

19835623921 is the 140839-th square number.

19835623921 is the 70420-th centered octagonal number.

It is an amenable number.

19835623921 is a deficient number, since it is larger than the sum of its proper divisors (140840).

19835623921 is an frugal number, since it uses more digits than its factorization.

19835623921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 281678 (or 140839 counting only the distinct ones).

The product of its digits is 699840, while the sum is 49.

Multiplying 19835623921 by its sum of digits (49), we get a square (971945572129 = 985873²).

The spelling of 19835623921 in words is "nineteen billion, eight hundred thirty-five million, six hundred twenty-three thousand, nine hundred twenty-one".