21256901 has 8 divisors (see below), whose sum is σ = 21840000. Its totient is φ = 20676960.

The previous prime is 21256867. The next prime is 21256909. The reversal of 21256901 is 10965212.

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 21256901 - 2¹⁴ = 21240517 is a prime.

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

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21256909) 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, 19940 + ... + 20978.

It is an arithmetic number, because the mean of its divisors is an integer number (2730000).

Almost surely, 2^21256901 is an apocalyptic number.

It is an amenable number.

21256901 is a deficient number, since it is larger than the sum of its proper divisors (583099).

21256901 is a wasteful number, since it uses less digits than its factorization.

21256901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1579.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 21256901 is about 4610.5206864301. The cubic root of 21256901 is about 277.0128932644.

The spelling of 21256901 in words is "twenty-one million, two hundred fifty-six thousand, nine hundred one".