221421207155631 has 16 divisors (see below), whose sum is σ = 337465801380864. Its totient is φ = 126503132660064.

The previous prime is 221421207155591. The next prime is 221421207155669. The reversal of 221421207155631 is 136551702124122.

It is not a de Polignac number, because 221421207155631 - 2⁶ = 221421207155567 is a prime.

It is a super-2 number, since 2×221421207155631² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221421207155531) 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, 969525975 + ... + 969754328.

It is an arithmetic number, because the mean of its divisors is an integer number (21091612586304).

Almost surely, 2^{221421207155631} is an apocalyptic number.

221421207155631 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221421207155631 is a deficient number, since it is larger than the sum of its proper divisors (116044594225233).

221421207155631 is a wasteful number, since it uses less digits than its factorization.

221421207155631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1939285750.

The product of its (nonzero) digits is 201600, while the sum is 42.

Adding to 221421207155631 its reverse (136551702124122), we get a palindrome (357972909279753).

The spelling of 221421207155631 in words is "two hundred twenty-one trillion, four hundred twenty-one billion, two hundred seven million, one hundred fifty-five thousand, six hundred thirty-one".