72042121 has 2 divisors, whose sum is σ = 72042122. Its totient is φ = 72042120.

The previous prime is 72042101. The next prime is 72042143. The reversal of 72042121 is 12124027.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 37994896 + 34047225 = 6164^2 + 5835^2 .

It is a cyclic number.

It is not a de Polignac number, because 72042121 - 2⁷ = 72041993 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (72042101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36021060 + 36021061.

It is an arithmetic number, because the mean of its divisors is an integer number (36021061).

Almost surely, 2^72042121 is an apocalyptic number.

It is an amenable number.

72042121 is a deficient number, since it is larger than the sum of its proper divisors (1).

72042121 is an equidigital number, since it uses as much as digits as its factorization.

72042121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 224, while the sum is 19.

The square root of 72042121 is about 8487.7630150706. The cubic root of 72042121 is about 416.0978739908.

Adding to 72042121 its reverse (12124027), we get a palindrome (84166148).

The spelling of 72042121 in words is "seventy-two million, forty-two thousand, one hundred twenty-one".