21455001 has 12 divisors (see below), whose sum is σ = 31030740. Its totient is φ = 14284800.

The previous prime is 21454997. The next prime is 21455011. The reversal of 21455001 is 10055412.

It can be written as a sum of positive squares in 2 ways, for example, as 15210000 + 6245001 = 3900^2 + 2499^2 .

It is not a de Polignac number, because 21455001 - 2² = 21454997 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21455011) 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 11 ways as a sum of consecutive naturals, for example, 12601 + ... + 14201.

It is an arithmetic number, because the mean of its divisors is an integer number (2585895).

Almost surely, 2^21455001 is an apocalyptic number.

It is an amenable number.

21455001 is a deficient number, since it is larger than the sum of its proper divisors (9575739).

21455001 is a wasteful number, since it uses less digits than its factorization.

21455001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3096 (or 3093 counting only the distinct ones).

The product of its (nonzero) digits is 200, while the sum is 18.

The square root of 21455001 is about 4631.9543391532. The cubic root of 21455001 is about 277.8707583783.

The spelling of 21455001 in words is "twenty-one million, four hundred fifty-five thousand, one".