203421661 has 2 divisors, whose sum is σ = 203421662. Its totient is φ = 203421660.

The previous prime is 203421649. The next prime is 203421667. The reversal of 203421661 is 166124302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 114704100 + 88717561 = 10710^2 + 9419^2 .

It is a cyclic number.

It is not a de Polignac number, because 203421661 - 2¹⁵ = 203388893 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (203421667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 101710830 + 101710831.

It is an arithmetic number, because the mean of its divisors is an integer number (101710831).

Almost surely, 2^203421661 is an apocalyptic number.

It is an amenable number.

203421661 is a deficient number, since it is larger than the sum of its proper divisors (1).

203421661 is an equidigital number, since it uses as much as digits as its factorization.

203421661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1728, while the sum is 25.

The square root of 203421661 is about 14262.5965728545. The cubic root of 203421661 is about 588.1197067972.

Adding to 203421661 its reverse (166124302), we get a palindrome (369545963).

The spelling of 203421661 in words is "two hundred three million, four hundred twenty-one thousand, six hundred sixty-one".