21288071 has 8 divisors (see below), whose sum is σ = 24360960. Its totient is φ = 18223128.

The previous prime is 21288067. The next prime is 21288079. The reversal of 21288071 is 17088212.

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

It is not a de Polignac number, because 21288071 - 2² = 21288067 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 (21288079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5810 + ... + 8736.

It is an arithmetic number, because the mean of its divisors is an integer number (3045120).

Almost surely, 2^21288071 is an apocalyptic number.

21288071 is a deficient number, since it is larger than the sum of its proper divisors (3072889).

21288071 is a wasteful number, since it uses less digits than its factorization.

21288071 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3973.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 21288071 is about 4613.8997605063. The cubic root of 21288071 is about 277.1482261763.

The spelling of 21288071 in words is "twenty-one million, two hundred eighty-eight thousand, seventy-one".