21276001 has 4 divisors (see below), whose sum is σ = 21312004. Its totient is φ = 21240000.

The previous prime is 21275983. The next prime is 21276023. The reversal of 21276001 is 10067212.

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

It can be written as a sum of positive squares in 2 ways, for example, as 11189025 + 10086976 = 3345^2 + 3176^2 .

It is a cyclic number.

It is not a de Polignac number, because 21276001 - 2⁷ = 21275873 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21276001.

It is not an unprimeable number, because it can be changed into a prime (21276071) 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, 17100 + ... + 18301.

It is an arithmetic number, because the mean of its divisors is an integer number (5328001).

Almost surely, 2^21276001 is an apocalyptic number.

It is an amenable number.

21276001 is a deficient number, since it is larger than the sum of its proper divisors (36003).

21276001 is an equidigital number, since it uses as much as digits as its factorization.

21276001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36002.

The product of its (nonzero) digits is 168, while the sum is 19.

The square root of 21276001 is about 4612.5915709068. The cubic root of 21276001 is about 277.0958367182.

It can be divided in two parts, 2127 and 6001, that added together give a triangular number (8128 = T₁₂₇).

The spelling of 21276001 in words is "twenty-one million, two hundred seventy-six thousand, one".