72177421 has 2 divisors, whose sum is σ = 72177422. Its totient is φ = 72177420.

The previous prime is 72177419. The next prime is 72177431. The reversal of 72177421 is 12477127.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 71149225 + 1028196 = 8435^2 + 1014^2 .

It is a cyclic number.

It is not a de Polignac number, because 72177421 - 2¹ = 72177419 is a prime.

It is a super-2 number, since 2×72177421² = 10419160204422482, which contains 22 as substring.

Together with 72177419, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (72177401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 36088710 + 36088711.

It is an arithmetic number, because the mean of its divisors is an integer number (36088711).

Almost surely, 2^72177421 is an apocalyptic number.

It is an amenable number.

72177421 is a deficient number, since it is larger than the sum of its proper divisors (1).

72177421 is an equidigital number, since it uses as much as digits as its factorization.

72177421 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5488, while the sum is 31.

The square root of 72177421 is about 8495.7295743214. The cubic root of 72177421 is about 416.3581977868.

The spelling of 72177421 in words is "seventy-two million, one hundred seventy-seven thousand, four hundred twenty-one".