21727939 has 8 divisors (see below), whose sum is σ = 22984992. Its totient is φ = 20496960.

The previous prime is 21727913. The next prime is 21727961. The reversal of 21727939 is 93972712.

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

It is a cyclic number.

It is not a de Polignac number, because 21727939 - 2¹⁵ = 21695171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21727999) 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, 4792 + ... + 8149.

It is an arithmetic number, because the mean of its divisors is an integer number (2873124).

Almost surely, 2^21727939 is an apocalyptic number.

21727939 is a deficient number, since it is larger than the sum of its proper divisors (1257053).

21727939 is a wasteful number, since it uses less digits than its factorization.

21727939 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13037.

The product of its digits is 47628, while the sum is 40.

The square root of 21727939 is about 4661.3237390252. The cubic root of 21727939 is about 279.0441000334.

The spelling of 21727939 in words is "twenty-one million, seven hundred twenty-seven thousand, nine hundred thirty-nine".