21250231 has 4 divisors (see below), whose sum is σ = 21393000. Its totient is φ = 21107464.

The previous prime is 21250217. The next prime is 21250253. The reversal of 21250231 is 13205212.

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

It is a cyclic number.

It is not a de Polignac number, because 21250231 - 2⁵ = 21250199 is a prime.

It is a super-2 number, since 2×21250231² = 903144635106722, 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 (21250211) 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, 71161 + ... + 71458.

It is an arithmetic number, because the mean of its divisors is an integer number (5348250).

Almost surely, 2^21250231 is an apocalyptic number.

21250231 is a deficient number, since it is larger than the sum of its proper divisors (142769).

21250231 is a wasteful number, since it uses less digits than its factorization.

21250231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 142768.

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21250231 is about 4609.7972840462. The cubic root of 21250231 is about 276.9839164898.

Adding to 21250231 its reverse (13205212), we get a palindrome (34455443).

The spelling of 21250231 in words is "twenty-one million, two hundred fifty thousand, two hundred thirty-one".