61518221 has 2 divisors, whose sum is σ = 61518222. Its totient is φ = 61518220.

The previous prime is 61518211. The next prime is 61518239. The reversal of 61518221 is 12281516.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45630025 + 15888196 = 6755^2 + 3986^2 .

It is a cyclic number.

It is not a de Polignac number, because 61518221 - 2⁶ = 61518157 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61518211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30759110 + 30759111.

It is an arithmetic number, because the mean of its divisors is an integer number (30759111).

Almost surely, 2^61518221 is an apocalyptic number.

It is an amenable number.

61518221 is a deficient number, since it is larger than the sum of its proper divisors (1).

61518221 is an equidigital number, since it uses as much as digits as its factorization.

61518221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 960, while the sum is 26.

The square root of 61518221 is about 7843.3552131725. The cubic root of 61518221 is about 394.7613171067.

Adding to 61518221 its reverse (12281516), we get a palindrome (73799737).

The spelling of 61518221 in words is "sixty-one million, five hundred eighteen thousand, two hundred twenty-one".