21256367 has 4 divisors (see below), whose sum is σ = 23188776. Its totient is φ = 19323960.

The previous prime is 21256331. The next prime is 21256369. The reversal of 21256367 is 76365212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21256367 - 2⁶ = 21256303 is a prime.

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

It is a Duffinian number.

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 (21256369) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 966188 + ... + 966209.

It is an arithmetic number, because the mean of its divisors is an integer number (5797194).

Almost surely, 2^21256367 is an apocalyptic number.

21256367 is a deficient number, since it is larger than the sum of its proper divisors (1932409).

21256367 is a wasteful number, since it uses less digits than its factorization.

21256367 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1932408.

The product of its digits is 15120, while the sum is 32.

The square root of 21256367 is about 4610.4627750368. The cubic root of 21256367 is about 277.0105736079.

The spelling of 21256367 in words is "twenty-one million, two hundred fifty-six thousand, three hundred sixty-seven".