21278071 has 8 divisors (see below), whose sum is σ = 21914144. Its totient is φ = 20645280.

The previous prime is 21278063. The next prime is 21278087. The reversal of 21278071 is 17087212.

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 21278071 - 2³ = 21278063 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 (21278021) 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, 19486 + ... + 20548.

It is an arithmetic number, because the mean of its divisors is an integer number (2739268).

Almost surely, 2^21278071 is an apocalyptic number.

21278071 is a deficient number, since it is larger than the sum of its proper divisors (636073).

21278071 is a wasteful number, since it uses less digits than its factorization.

21278071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1641.

The product of its (nonzero) digits is 1568, while the sum is 28.

The square root of 21278071 is about 4612.8159512385. The cubic root of 21278071 is about 277.1048228960.

The spelling of 21278071 in words is "twenty-one million, two hundred seventy-eight thousand, seventy-one".