21231001 has 16 divisors (see below), whose sum is σ = 24956928. Its totient is φ = 17859600.

The previous prime is 21230969. The next prime is 21231029. The reversal of 21231001 is 10013212.

It is not a de Polignac number, because 21231001 - 2⁵ = 21230969 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21231601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6490 + ... + 9196.

It is an arithmetic number, because the mean of its divisors is an integer number (1559808).

Almost surely, 2^21231001 is an apocalyptic number.

It is an amenable number.

21231001 is a deficient number, since it is larger than the sum of its proper divisors (3725927).

21231001 is a wasteful number, since it uses less digits than its factorization.

21231001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2772.

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21231001 is about 4607.7110369467. The cubic root of 21231001 is about 276.9003407992.

Adding to 21231001 its reverse (10013212), we get a palindrome (31244213).

It can be divided in two parts, 212 and 31001, that added together give a palindrome (31213).

The spelling of 21231001 in words is "twenty-one million, two hundred thirty-one thousand, one".