21709893 has 8 divisors (see below), whose sum is σ = 29944800. Its totient is φ = 13974128.

The previous prime is 21709879. The next prime is 21709903. The reversal of 21709893 is 39890712.

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 21709893 - 2⁶ = 21709829 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21709813) 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, 124683 + ... + 124856.

It is an arithmetic number, because the mean of its divisors is an integer number (3743100).

Almost surely, 2^21709893 is an apocalyptic number.

It is an amenable number.

21709893 is a deficient number, since it is larger than the sum of its proper divisors (8234907).

21709893 is a wasteful number, since it uses less digits than its factorization.

21709893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 249571.

The product of its (nonzero) digits is 27216, while the sum is 39.

The square root of 21709893 is about 4659.3876207073. The cubic root of 21709893 is about 278.9668258754.

The spelling of 21709893 in words is "twenty-one million, seven hundred nine thousand, eight hundred ninety-three".