221421651551 has 16 divisors (see below), whose sum is σ = 230483957760. Its totient is φ = 212485484640.

The previous prime is 221421651509. The next prime is 221421651569. The reversal of 221421651551 is 155156124122.

It is a cyclic number.

It is not a de Polignac number, because 221421651551 - 2¹⁸ = 221421389407 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221421551551) 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, 2118125 + ... + 2220201.

It is an arithmetic number, because the mean of its divisors is an integer number (14405247360).

Almost surely, 2^221421651551 is an apocalyptic number.

221421651551 is a deficient number, since it is larger than the sum of its proper divisors (9062306209).

221421651551 is a wasteful number, since it uses less digits than its factorization.

221421651551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 102694.

The product of its digits is 24000, while the sum is 35.

Adding to 221421651551 its reverse (155156124122), we get a palindrome (376577775673).

The spelling of 221421651551 in words is "two hundred twenty-one billion, four hundred twenty-one million, six hundred fifty-one thousand, five hundred fifty-one".