221421651591 has 64 divisors (see below), whose sum is σ = 346850380800. Its totient is φ = 123034982400.

The previous prime is 221421651589. The next prime is 221421651707. The reversal of 221421651591 is 195156124122.

It is not a de Polignac number, because 221421651591 - 2¹ = 221421651589 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221421651091) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 118979001 + ... + 118980861.

It is an arithmetic number, because the mean of its divisors is an integer number (5419537200).

Almost surely, 2^221421651591 is an apocalyptic number.

221421651591 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

221421651591 is a deficient number, since it is larger than the sum of its proper divisors (125428729209).

221421651591 is a wasteful number, since it uses less digits than its factorization.

221421651591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2920.

The product of its digits is 43200, while the sum is 39.

The spelling of 221421651591 in words is "two hundred twenty-one billion, four hundred twenty-one million, six hundred fifty-one thousand, five hundred ninety-one".