61515221 has 2 divisors, whose sum is σ = 61515222. Its totient is φ = 61515220.

The previous prime is 61515193. The next prime is 61515239. The reversal of 61515221 is 12251516.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 58828900 + 2686321 = 7670^2 + 1639^2 .

It is a cyclic number.

It is not a de Polignac number, because 61515221 - 2¹⁰ = 61514197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (61515281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30757610 + 30757611.

It is an arithmetic number, because the mean of its divisors is an integer number (30757611).

Almost surely, 2^61515221 is an apocalyptic number.

It is an amenable number.

61515221 is a deficient number, since it is larger than the sum of its proper divisors (1).

61515221 is an equidigital number, since it uses as much as digits as its factorization.

61515221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 600, while the sum is 23.

The square root of 61515221 is about 7843.1639661555. The cubic root of 61515221 is about 394.7549000204.

Adding to 61515221 its reverse (12251516), we get a palindrome (73766737).

The spelling of 61515221 in words is "sixty-one million, five hundred fifteen thousand, two hundred twenty-one".