21998727 has 24 divisors (see below), whose sum is σ = 32532864. Its totient is φ = 14321664.

The previous prime is 21998723. The next prime is 21998749. The reversal of 21998727 is 72789912.

It is not a de Polignac number, because 21998727 - 2² = 21998723 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21998723) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 98538 + ... + 98760.

It is an arithmetic number, because the mean of its divisors is an integer number (1355536).

Almost surely, 2^21998727 is an apocalyptic number.

21998727 is a deficient number, since it is larger than the sum of its proper divisors (10534137).

21998727 is a wasteful number, since it uses less digits than its factorization.

21998727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 439 (or 436 counting only the distinct ones).

The product of its digits is 127008, while the sum is 45.

The square root of 21998727 is about 4690.2800556044. The cubic root of 21998727 is about 280.1985284218.

The spelling of 21998727 in words is "twenty-one million, nine hundred ninety-eight thousand, seven hundred twenty-seven".