21256071 has 16 divisors (see below), whose sum is σ = 29756160. Its totient is φ = 13471040.

The previous prime is 21256057. The next prime is 21256087. The reversal of 21256071 is 17065212.

It is a cyclic number.

It is not a de Polignac number, because 21256071 - 2¹⁹ = 20731783 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256471) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11491 + ... + 13211.

It is an arithmetic number, because the mean of its divisors is an integer number (1859760).

Almost surely, 2^21256071 is an apocalyptic number.

21256071 is a deficient number, since it is larger than the sum of its proper divisors (8500089).

21256071 is a wasteful number, since it uses less digits than its factorization.

21256071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1926.

The product of its (nonzero) digits is 840, while the sum is 24.

The square root of 21256071 is about 4610.4306740260. The cubic root of 21256071 is about 277.0092877891.

The spelling of 21256071 in words is "twenty-one million, two hundred fifty-six thousand, seventy-one".