221531223531 has 16 divisors (see below), whose sum is σ = 322838673408. Its totient is φ = 134516112000.

The previous prime is 221531223527. The next prime is 221531223547. The reversal of 221531223531 is 135322135122.

It is not a de Polignac number, because 221531223531 - 2² = 221531223527 is a prime.

It is a super-2 number, since 2×221531223531² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (221531223031) 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, 70058895 + ... + 70062056.

It is an arithmetic number, because the mean of its divisors is an integer number (20177417088).

Almost surely, 2^221531223531 is an apocalyptic number.

221531223531 is a deficient number, since it is larger than the sum of its proper divisors (101307449877).

221531223531 is a wasteful number, since it uses less digits than its factorization.

221531223531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 140121002.

The product of its digits is 10800, while the sum is 30.

Adding to 221531223531 its reverse (135322135122), we get a palindrome (356853358653).

The spelling of 221531223531 in words is "two hundred twenty-one billion, five hundred thirty-one million, two hundred twenty-three thousand, five hundred thirty-one".