19921400 has 24 divisors (see below), whose sum is σ = 46317720. Its totient is φ = 7968480.

The previous prime is 19921387. The next prime is 19921417. The reversal of 19921400 is 412991.

It is a self number, because there is not a number n which added to its sum of digits gives 19921400.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 49604 + ... + 50003.

It is an arithmetic number, because the mean of its divisors is an integer number (1929905).

Almost surely, 2^19921400 is an apocalyptic number.

19921400 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19921400 is an abundant number, since it is smaller than the sum of its proper divisors (26396320).

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

19921400 is a wasteful number, since it uses less digits than its factorization.

19921400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 99623 (or 99614 counting only the distinct ones).

The product of its (nonzero) digits is 648, while the sum is 26.

The square root of 19921400 is about 4463.3395568789. The cubic root of 19921400 is about 271.0857061108.

The spelling of 19921400 in words is "nineteen million, nine hundred twenty-one thousand, four hundred".