21276521 has 8 divisors (see below), whose sum is σ = 24728640. Its totient is φ = 17927568.

The previous prime is 21276491. The next prime is 21276547. The reversal of 21276521 is 12567212.

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 21276521 - 2⁶ = 21276457 is a prime.

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

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21276551) 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, 25346 + ... + 26171.

It is an arithmetic number, because the mean of its divisors is an integer number (3091080).

Almost surely, 2^21276521 is an apocalyptic number.

It is an amenable number.

21276521 is a deficient number, since it is larger than the sum of its proper divisors (3452119).

21276521 is an equidigital number, since it uses as much as digits as its factorization.

21276521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51583.

The product of its digits is 1680, while the sum is 26.

The square root of 21276521 is about 4612.6479380070. The cubic root of 21276521 is about 277.0980941703.

The spelling of 21276521 in words is "twenty-one million, two hundred seventy-six thousand, five hundred twenty-one".