21051198 has 32 divisors (see below), whose sum is σ = 53464320. Its totient is φ = 6014520.

The previous prime is 21051197. The next prime is 21051203. The reversal of 21051198 is 89115012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051193) 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, 27468 + ... + 28223.

It is an arithmetic number, because the mean of its divisors is an integer number (1670760).

Almost surely, 2^21051198 is an apocalyptic number.

21051198 is an abundant number, since it is smaller than the sum of its proper divisors (32413122).

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

21051198 is a wasteful number, since it uses less digits than its factorization.

21051198 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55709 (or 55703 counting only the distinct ones).

The product of its (nonzero) digits is 720, while the sum is 27.

The square root of 21051198 is about 4588.1584541077. The cubic root of 21051198 is about 276.1164442491.

The spelling of 21051198 in words is "twenty-one million, fifty-one thousand, one hundred ninety-eight".