221545031 has 4 divisors (see below), whose sum is σ = 221629992. Its totient is φ = 221460072.

The previous prime is 221545013. The next prime is 221545033. The reversal of 221545031 is 130545122.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221545031 is a prime.

It is a super-2 number, since 2×221545031² = 98164401521581922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 221544988 and 221545006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221545033) 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, 38441 + ... + 43826.

It is an arithmetic number, because the mean of its divisors is an integer number (55407498).

Almost surely, 2^221545031 is an apocalyptic number.

221545031 is a deficient number, since it is larger than the sum of its proper divisors (84961).

221545031 is an equidigital number, since it uses as much as digits as its factorization.

221545031 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84960.

The product of its (nonzero) digits is 1200, while the sum is 23.

The square root of 221545031 is about 14884.3888352865. The cubic root of 221545031 is about 605.0909691773.

Subtracting from 221545031 its reverse (130545122), we obtain a palindrome (90999909).

The spelling of 221545031 in words is "two hundred twenty-one million, five hundred forty-five thousand, thirty-one".