21032001 has 8 divisors (see below), whose sum is σ = 31158560. Its totient is φ = 14021316.

The previous prime is 21031979. The next prime is 21032003. The reversal of 21032001 is 10023012.

It is a happy number.

It is not a de Polignac number, because 21032001 - 2¹⁸ = 20769857 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21032003) 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, 389455 + ... + 389508.

It is an arithmetic number, because the mean of its divisors is an integer number (3894820).

Almost surely, 2^21032001 is an apocalyptic number.

It is an amenable number.

21032001 is a deficient number, since it is larger than the sum of its proper divisors (10126559).

21032001 is an equidigital number, since it uses as much as digits as its factorization.

21032001 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 778972 (or 778966 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21032001 is about 4586.0659611480. The cubic root of 21032001 is about 276.0324867242.

Adding to 21032001 its reverse (10023012), we get a palindrome (31055013).

The spelling of 21032001 in words is "twenty-one million, thirty-two thousand, one".