21698727 has 4 divisors (see below), whose sum is σ = 28931640. Its totient is φ = 14465816.

The previous prime is 21698713. The next prime is 21698731. The reversal of 21698727 is 72789612.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21698727 - 2⁴ = 21698711 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21698707) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3616452 + ... + 3616457.

It is an arithmetic number, because the mean of its divisors is an integer number (7232910).

Almost surely, 2^21698727 is an apocalyptic number.

21698727 is a deficient number, since it is larger than the sum of its proper divisors (7232913).

21698727 is an equidigital number, since it uses as much as digits as its factorization.

21698727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7232912.

The product of its digits is 84672, while the sum is 42.

The square root of 21698727 is about 4658.1892404667. The cubic root of 21698727 is about 278.9189908820.

The spelling of 21698727 in words is "twenty-one million, six hundred ninety-eight thousand, seven hundred twenty-seven".