221631457 has 2 divisors, whose sum is σ = 221631458. Its totient is φ = 221631456.

The previous prime is 221631439. The next prime is 221631463. The reversal of 221631457 is 754136122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 165920161 + 55711296 = 12881^2 + 7464^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-221631457 is a 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, 110815728 + 110815729.

It is an arithmetic number, because the mean of its divisors is an integer number (110815729).

Almost surely, 2^221631457 is an apocalyptic number.

It is an amenable number.

221631457 is a deficient number, since it is larger than the sum of its proper divisors (1).

221631457 is an equidigital number, since it uses as much as digits as its factorization.

221631457 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10080, while the sum is 31.

The square root of 221631457 is about 14887.2917953535. The cubic root of 221631457 is about 605.1696421121.

Adding to 221631457 its reverse (754136122), we get a palindrome (975767579).

The spelling of 221631457 in words is "two hundred twenty-one million, six hundred thirty-one thousand, four hundred fifty-seven".