21019998 has 32 divisors (see below), whose sum is σ = 43338240. Its totient is φ = 6793280.

The previous prime is 21019993. The next prime is 21020011. The reversal of 21019998 is 89991012.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21019993) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 36658 + ... + 37226.

It is an arithmetic number, because the mean of its divisors is an integer number (1354320).

Almost surely, 2^21019998 is an apocalyptic number.

21019998 is an abundant number, since it is smaller than the sum of its proper divisors (22318242).

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

21019998 is a wasteful number, since it uses less digits than its factorization.

21019998 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 752.

The product of its (nonzero) digits is 11664, while the sum is 39.

The square root of 21019998 is about 4584.7571364250. The cubic root of 21019998 is about 275.9799659896.

It can be divided in two parts, 210199 and 98, that multiplied together give a palindrome (20599502).

The spelling of 21019998 in words is "twenty-one million, nineteen thousand, nine hundred ninety-eight".