221951289 has 16 divisors (see below), whose sum is σ = 349122560. Its totient is φ = 122737680.

The previous prime is 221951287. The next prime is 221951329. The reversal of 221951289 is 982159122.

It is not a de Polignac number, because 221951289 - 2¹ = 221951287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221951287) 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, 169819 + ... + 171120.

It is an arithmetic number, because the mean of its divisors is an integer number (21820160).

Almost surely, 2^221951289 is an apocalyptic number.

It is an amenable number.

221951289 is a deficient number, since it is larger than the sum of its proper divisors (127171271).

221951289 is a wasteful number, since it uses less digits than its factorization.

221951289 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 340980.

The product of its digits is 25920, while the sum is 39.

The square root of 221951289 is about 14898.0297019438. The cubic root of 221951289 is about 605.4606050018.

It can be divided in two parts, 221 and 951289, that added together give a triangular number (951510 = T₁₃₇₉).

The spelling of 221951289 in words is "two hundred twenty-one million, nine hundred fifty-one thousand, two hundred eighty-nine".