21021698 has 16 divisors (see below), whose sum is σ = 32922744. Its totient is φ = 10056960.

The previous prime is 21021697. The next prime is 21021703. The reversal of 21021698 is 89612012.

It can be written as a sum of positive squares in 4 ways, for example, as 12652249 + 8369449 = 3557^2 + 2893^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21021698.

It is not an unprimeable number, because it can be changed into a prime (21021697) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2186 + ... + 6842.

Almost surely, 2^21021698 is an apocalyptic number.

21021698 is a deficient number, since it is larger than the sum of its proper divisors (11901046).

21021698 is a wasteful number, since it uses less digits than its factorization.

21021698 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4757.

The product of its (nonzero) digits is 1728, while the sum is 29.

The square root of 21021698 is about 4584.9425296289. The cubic root of 21021698 is about 275.9874057825.

The spelling of 21021698 in words is "twenty-one million, twenty-one thousand, six hundred ninety-eight".