221378081 has 4 divisors (see below), whose sum is σ = 221852592. Its totient is φ = 220903572.

The previous prime is 221378077. The next prime is 221378107. The reversal of 221378081 is 180873122.

221378081 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 221378081 - 2² = 221378077 is a prime.

It is a super-2 number, since 2×221378081² = 98016509494485122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (221378041) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 236555 + ... + 237488.

It is an arithmetic number, because the mean of its divisors is an integer number (55463148).

Almost surely, 2^221378081 is an apocalyptic number.

It is an amenable number.

221378081 is a deficient number, since it is larger than the sum of its proper divisors (474511).

221378081 is an equidigital number, since it uses as much as digits as its factorization.

221378081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 474510.

The product of its (nonzero) digits is 5376, while the sum is 32.

The square root of 221378081 is about 14878.7795534446. The cubic root of 221378081 is about 604.9389378985.

The spelling of 221378081 in words is "two hundred twenty-one million, three hundred seventy-eight thousand, eighty-one".