21988727 has 4 divisors (see below), whose sum is σ = 22012080. Its totient is φ = 21965376.

The previous prime is 21988721. The next prime is 21988739. The reversal of 21988727 is 72788912.

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 21988727 - 2⁴ = 21988711 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21988721) 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, 10202 + ... + 12167.

It is an arithmetic number, because the mean of its divisors is an integer number (5503020).

Almost surely, 2^21988727 is an apocalyptic number.

21988727 is a deficient number, since it is larger than the sum of its proper divisors (23353).

21988727 is an equidigital number, since it uses as much as digits as its factorization.

21988727 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23352.

The product of its digits is 112896, while the sum is 44.

The square root of 21988727 is about 4689.2139000050. The cubic root of 21988727 is about 280.1560652078.

The spelling of 21988727 in words is "twenty-one million, nine hundred eighty-eight thousand, seven hundred twenty-seven".