201221551 has 2 divisors, whose sum is σ = 201221552. Its totient is φ = 201221550.

The previous prime is 201221539. The next prime is 201221557. The reversal of 201221551 is 155122102.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-201221551 is a prime.

It is a super-2 number, since 2×201221551² = 80980225173691202, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (201221557) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 100610775 + 100610776.

It is an arithmetic number, because the mean of its divisors is an integer number (100610776).

Almost surely, 2^201221551 is an apocalyptic number.

201221551 is a deficient number, since it is larger than the sum of its proper divisors (1).

201221551 is an equidigital number, since it uses as much as digits as its factorization.

201221551 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 200, while the sum is 19.

The square root of 201221551 is about 14185.2582281748. The cubic root of 201221551 is about 585.9917441090.

Adding to 201221551 its reverse (155122102), we get a palindrome (356343653).

The spelling of 201221551 in words is "two hundred one million, two hundred twenty-one thousand, five hundred fifty-one".