221651365710551 has 12 divisors (see below), whose sum is σ = 257876395388640. Its totient is φ = 189959583713760.

The previous prime is 221651365710443. The next prime is 221651365710581. The reversal of 221651365710551 is 155017563156122.

It is not a de Polignac number, because 221651365710551 - 2⁴² = 217253319199447 is a prime.

It is a super-2 number, since 2×221651365710551² (a number of 29 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 221651365710551.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221651365710581) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 324669590 + ... + 325351571.

It is an arithmetic number, because the mean of its divisors is an integer number (21489699615720).

Almost surely, 2^{221651365710551} is an apocalyptic number.

221651365710551 is a deficient number, since it is larger than the sum of its proper divisors (36225029678089).

221651365710551 is an equidigital number, since it uses as much as digits as its factorization.

221651365710551 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 650028134 (or 650028127 counting only the distinct ones).

The product of its (nonzero) digits is 1890000, while the sum is 50.

The spelling of 221651365710551 in words is "two hundred twenty-one trillion, six hundred fifty-one billion, three hundred sixty-five million, seven hundred ten thousand, five hundred fifty-one".