72121757 has 2 divisors, whose sum is σ = 72121758. Its totient is φ = 72121756.

The previous prime is 72121697. The next prime is 72121787. The reversal of 72121757 is 75712127.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72012196 + 109561 = 8486^2 + 331^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-72121757 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72121787) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36060878 + 36060879.

It is an arithmetic number, because the mean of its divisors is an integer number (36060879).

Almost surely, 2^72121757 is an apocalyptic number.

It is an amenable number.

72121757 is a deficient number, since it is larger than the sum of its proper divisors (1).

72121757 is an equidigital number, since it uses as much as digits as its factorization.

72121757 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6860, while the sum is 32.

The square root of 72121757 is about 8492.4529436436. The cubic root of 72121757 is about 416.2511369597.

The spelling of 72121757 in words is "seventy-two million, one hundred twenty-one thousand, seven hundred fifty-seven".