221661461 has 4 divisors (see below), whose sum is σ = 253327392. Its totient is φ = 189995532.

The previous prime is 221661443. The next prime is 221661491. The reversal of 221661461 is 164166122.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 221661461 - 2¹⁰ = 221660437 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 (221661491) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15832955 + ... + 15832968.

It is an arithmetic number, because the mean of its divisors is an integer number (63331848).

Almost surely, 2^221661461 is an apocalyptic number.

It is an amenable number.

221661461 is a deficient number, since it is larger than the sum of its proper divisors (31665931).

221661461 is an equidigital number, since it uses as much as digits as its factorization.

221661461 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31665930.

The product of its digits is 3456, while the sum is 29.

The square root of 221661461 is about 14888.2994663595. The cubic root of 221661461 is about 605.1969497438.

The spelling of 221661461 in words is "two hundred twenty-one million, six hundred sixty-one thousand, four hundred sixty-one".