75043721 has 2 divisors, whose sum is σ = 75043722. Its totient is φ = 75043720.

The previous prime is 75043699. The next prime is 75043723. The reversal of 75043721 is 12734057.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 37650496 + 37393225 = 6136^2 + 6115^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-75043721 is a prime.

Together with 75043723, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (75043723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37521860 + 37521861.

It is an arithmetic number, because the mean of its divisors is an integer number (37521861).

Almost surely, 2^75043721 is an apocalyptic number.

It is an amenable number.

75043721 is a deficient number, since it is larger than the sum of its proper divisors (1).

75043721 is an equidigital number, since it uses as much as digits as its factorization.

75043721 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 75043721 is about 8662.7779031902. Note that the first 3 decimals coincide. The cubic root of 75043721 is about 421.7982627761.

Adding to 75043721 its reverse (12734057), we get a palindrome (87777778).

It can be divided in two parts, 75043 and 721, that multiplied together give a triangular number (54106003 = T₁₀₄₀₂).

The spelling of 75043721 in words is "seventy-five million, forty-three thousand, seven hundred twenty-one".