19921398 has 16 divisors (see below), whose sum is σ = 45534720. Its totient is φ = 5691816.

The previous prime is 19921387. The next prime is 19921417. The reversal of 19921398 is 89312991.

It is a Harshad number since it is a multiple of its sum of digits (42), and also a Moran number because the ratio is a prime number: 474319 = 19921398 / (1 + 9 + 9 + 2 + 1 + 3 + 9 + 8).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 237118 + ... + 237201.

It is an arithmetic number, because the mean of its divisors is an integer number (2845920).

Almost surely, 2^19921398 is an apocalyptic number.

19921398 is an abundant number, since it is smaller than the sum of its proper divisors (25613322).

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

19921398 is a wasteful number, since it uses less digits than its factorization.

19921398 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474331.

The product of its digits is 34992, while the sum is 42.

The square root of 19921398 is about 4463.3393328314. The cubic root of 19921398 is about 271.0856970390.

The spelling of 19921398 in words is "nineteen million, nine hundred twenty-one thousand, three hundred ninety-eight".