221651421 has 16 divisors (see below), whose sum is σ = 302382720. Its totient is φ = 144381440.

The previous prime is 221651407. The next prime is 221651431. The reversal of 221651421 is 124156122.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221651421 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 221651391 and 221651400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221651431) 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, 19465 + ... + 28673.

It is an arithmetic number, because the mean of its divisors is an integer number (18898920).

Almost surely, 2^221651421 is an apocalyptic number.

It is an amenable number.

221651421 is a deficient number, since it is larger than the sum of its proper divisors (80731299).

221651421 is a wasteful number, since it uses less digits than its factorization.

221651421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9396.

The product of its digits is 960, while the sum is 24.

The square root of 221651421 is about 14887.9622850140. The cubic root of 221651421 is about 605.1878122825.

The spelling of 221651421 in words is "two hundred twenty-one million, six hundred fifty-one thousand, four hundred twenty-one".