75815221 has 2 divisors, whose sum is σ = 75815222. Its totient is φ = 75815220.

The previous prime is 75815209. The next prime is 75815239. The reversal of 75815221 is 12251857.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 67486225 + 8328996 = 8215^2 + 2886^2 .

It is a cyclic number.

It is not a de Polignac number, because 75815221 - 2⁷ = 75815093 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (75815261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37907610 + 37907611.

It is an arithmetic number, because the mean of its divisors is an integer number (37907611).

Almost surely, 2^75815221 is an apocalyptic number.

It is an amenable number.

75815221 is a deficient number, since it is larger than the sum of its proper divisors (1).

75815221 is an equidigital number, since it uses as much as digits as its factorization.

75815221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 5600, while the sum is 31.

The square root of 75815221 is about 8707.1936351502. The cubic root of 75815221 is about 423.2387942044.

The spelling of 75815221 in words is "seventy-five million, eight hundred fifteen thousand, two hundred twenty-one".