21317727 has 8 divisors (see below), whose sum is σ = 28612480. Its totient is φ = 14117400.

The previous prime is 21317719. The next prime is 21317729. The reversal of 21317727 is 72771312.

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

It is not a de Polignac number, because 21317727 - 2³ = 21317719 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21317694 and 21317703.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21317729) 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, 23077 + ... + 23982.

It is an arithmetic number, because the mean of its divisors is an integer number (3576560).

Almost surely, 2^21317727 is an apocalyptic number.

21317727 is a deficient number, since it is larger than the sum of its proper divisors (7294753).

21317727 is a wasteful number, since it uses less digits than its factorization.

21317727 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47213.

The product of its digits is 4116, while the sum is 30.

The square root of 21317727 is about 4617.1124092879. The cubic root of 21317727 is about 277.2768630722.

The spelling of 21317727 in words is "twenty-one million, three hundred seventeen thousand, seven hundred twenty-seven".