221949021 has 12 divisors (see below), whose sum is σ = 338312096. Its totient is φ = 126789000.

The previous prime is 221949019. The next prime is 221949029. The reversal of 221949021 is 120949122.

It is a happy number.

It is not a de Polignac number, because 221949021 - 2¹ = 221949019 is a prime.

It is a super-2 number, since 2×221949021² = 98522735845716882, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 221949021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221949029) 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, 66646 + ... + 69896.

Almost surely, 2^221949021 is an apocalyptic number.

221949021 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

221949021 is a deficient number, since it is larger than the sum of its proper divisors (116363075).

221949021 is an frugal number, since it uses more digits than its factorization.

221949021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6512 (or 3261 counting only the distinct ones).

The product of its (nonzero) digits is 2592, while the sum is 30.

The square root of 221949021 is about 14897.9535843014. The cubic root of 221949021 is about 605.4585427035.

The spelling of 221949021 in words is "two hundred twenty-one million, nine hundred forty-nine thousand, twenty-one".