21031001 has 4 divisors (see below), whose sum is σ = 21058512. Its totient is φ = 21003492.

The previous prime is 21030979. The next prime is 21031009. The reversal of 21031001 is 10013012.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21031001 - 2¹⁰ = 21029977 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 21031001.

It is not an unprimeable number, because it can be changed into a prime (21031009) 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, 12575 + ... + 14148.

It is an arithmetic number, because the mean of its divisors is an integer number (5264628).

Almost surely, 2^21031001 is an apocalyptic number.

It is an amenable number.

21031001 is a deficient number, since it is larger than the sum of its proper divisors (27511).

21031001 is an equidigital number, since it uses as much as digits as its factorization.

21031001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27510.

The product of its (nonzero) digits is 6, while the sum is 8.

The square root of 21031001 is about 4585.9569339452. The cubic root of 21031001 is about 276.0281118534.

Adding to 21031001 its reverse (10013012), we get a palindrome (31044013).

The spelling of 21031001 in words is "twenty-one million, thirty-one thousand, one".