221631401 has 2 divisors, whose sum is σ = 221631402. Its totient is φ = 221631400.

The previous prime is 221631373. The next prime is 221631407. The reversal of 221631401 is 104136122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 220819600 + 811801 = 14860^2 + 901^2 .

It is a cyclic number.

It is not a de Polignac number, because 221631401 - 2⁶ = 221631337 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is equal to p_12207413 and since 221631401 and 12207413 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (221631407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110815700 + 110815701.

It is an arithmetic number, because the mean of its divisors is an integer number (110815701).

Almost surely, 2^221631401 is an apocalyptic number.

It is an amenable number.

221631401 is a deficient number, since it is larger than the sum of its proper divisors (1).

221631401 is an equidigital number, since it uses as much as digits as its factorization.

221631401 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 221631401 is about 14887.2899145546. The cubic root of 221631401 is about 605.1695911423.

Adding to 221631401 its reverse (104136122), we get a palindrome (325767523).

The spelling of 221631401 in words is "two hundred twenty-one million, six hundred thirty-one thousand, four hundred one".