19921000 has 64 divisors (see below), whose sum is σ = 50880960. Its totient is φ = 7240000.

The previous prime is 19920973. The next prime is 19921021. The reversal of 19921000 is 12991.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10095 + ... + 11905.

It is an arithmetic number, because the mean of its divisors is an integer number (795015).

Almost surely, 2^19921000 is an apocalyptic number.

19921000 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19921000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25440480).

19921000 is an abundant number, since it is smaller than the sum of its proper divisors (30959960).

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

19921000 is a wasteful number, since it uses less digits than its factorization.

19921000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1843 (or 1829 counting only the distinct ones).

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 19921000 is about 4463.2947471571. The cubic root of 19921000 is about 271.0838917301.

Adding to 19921000 its reverse (12991), we get a palindrome (19933991).

It can be divided in two parts, 1992 and 1000, that added together give a palindrome (2992).

The spelling of 19921000 in words is "nineteen million, nine hundred twenty-one thousand".