221497397 has 6 divisors (see below), whose sum is σ = 243464214. Its totient is φ = 201361160.

The previous prime is 221497391. The next prime is 221497427. The reversal of 221497397 is 793794122.

221497397 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 216943441 + 4553956 = 14729^2 + 2134^2 .

It is not a de Polignac number, because 221497397 - 2⁶ = 221497333 is a prime.

It is a super-2 number, since 2×221497397² = 98122193755551218, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (221497391) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 915158 + ... + 915399.

It is an arithmetic number, because the mean of its divisors is an integer number (40577369).

Almost surely, 2^221497397 is an apocalyptic number.

It is an amenable number.

221497397 is a deficient number, since it is larger than the sum of its proper divisors (21966817).

221497397 is a wasteful number, since it uses less digits than its factorization.

221497397 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1830579 (or 1830568 counting only the distinct ones).

The product of its digits is 190512, while the sum is 44.

The square root of 221497397 is about 14882.7886163850. The cubic root of 221497397 is about 605.0475995607.

The spelling of 221497397 in words is "two hundred twenty-one million, four hundred ninety-seven thousand, three hundred ninety-seven".