21256143 has 8 divisors (see below), whose sum is σ = 28433328. Its totient is φ = 14124864.

The previous prime is 21256129. The next prime is 21256153. The reversal of 21256143 is 34165212.

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

It is not a de Polignac number, because 21256143 - 2¹² = 21252047 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256153) 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, 10380 + ... + 12257.

It is an arithmetic number, because the mean of its divisors is an integer number (3554166).

Almost surely, 2^21256143 is an apocalyptic number.

21256143 is a deficient number, since it is larger than the sum of its proper divisors (7177185).

21256143 is a wasteful number, since it uses less digits than its factorization.

21256143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22953.

The product of its digits is 1440, while the sum is 24.

The square root of 21256143 is about 4610.4384824006. The cubic root of 21256143 is about 277.0096005570.

The spelling of 21256143 in words is "twenty-one million, two hundred fifty-six thousand, one hundred forty-three".