21552001 has 4 divisors (see below), whose sum is σ = 21591252. Its totient is φ = 21512752.

The previous prime is 21551993. The next prime is 21552007. The reversal of 21552001 is 10025512.

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 9828225 + 11723776 = 3135^2 + 3424^2 .

It is a cyclic number.

It is not a de Polignac number, because 21552001 - 2³ = 21551993 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21552007) 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 3 ways as a sum of consecutive naturals, for example, 18790 + ... + 19903.

It is an arithmetic number, because the mean of its divisors is an integer number (5397813).

Almost surely, 2^21552001 is an apocalyptic number.

It is an amenable number.

21552001 is a deficient number, since it is larger than the sum of its proper divisors (39251).

21552001 is an equidigital number, since it uses as much as digits as its factorization.

21552001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39250.

The product of its (nonzero) digits is 100, while the sum is 16.

The square root of 21552001 is about 4642.4132732879. The cubic root of 21552001 is about 278.2888884854.

Adding to 21552001 its reverse (10025512), we get a palindrome (31577513).

The spelling of 21552001 in words is "twenty-one million, five hundred fifty-two thousand, one".