21202231 has 4 divisors (see below), whose sum is σ = 21236464. Its totient is φ = 21168000.

The previous prime is 21202211. The next prime is 21202261. The reversal of 21202231 is 13220212.

It is a semiprime because it is the product of two primes.

It is a 7-Lehmer number, since φ(21202231) divides (21202231-1)⁷.

It is a cyclic number.

It is not a de Polignac number, because 21202231 - 2⁵ = 21202199 is a prime.

It is a super-2 number, since 2×21202231² = 899069198754722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21202201) 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, 16170 + ... + 17431.

It is an arithmetic number, because the mean of its divisors is an integer number (5309116).

Almost surely, 2^21202231 is an apocalyptic number.

21202231 is a deficient number, since it is larger than the sum of its proper divisors (34233).

21202231 is an equidigital number, since it uses as much as digits as its factorization.

21202231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34232.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21202231 is about 4604.5880380334. The cubic root of 21202231 is about 276.7752089392.

Adding to 21202231 its reverse (13220212), we get a palindrome (34422443).

The spelling of 21202231 in words is "twenty-one million, two hundred two thousand, two hundred thirty-one".