21198745 has 8 divisors (see below), whose sum is σ = 26934984. Its totient is φ = 15961344.

The previous prime is 21198731. The next prime is 21198757. The reversal of 21198745 is 54789112.

It can be written as a sum of positive squares in 4 ways, for example, as 5294601 + 15904144 = 2301^2 + 3988^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21198745 - 2¹¹ = 21196697 is a prime.

It is a Duffinian 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, 124614 + ... + 124783.

It is an arithmetic number, because the mean of its divisors is an integer number (3366873).

Almost surely, 2^21198745 is an apocalyptic number.

It is an amenable number.

21198745 is a deficient number, since it is larger than the sum of its proper divisors (5736239).

21198745 is a wasteful number, since it uses less digits than its factorization.

21198745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249419.

The product of its digits is 20160, while the sum is 37.

The square root of 21198745 is about 4604.2094869804. The cubic root of 21198745 is about 276.7600392893.

The spelling of 21198745 in words is "twenty-one million, one hundred ninety-eight thousand, seven hundred forty-five".