67729421 has 2 divisors, whose sum is σ = 67729422. Its totient is φ = 67729420.

The previous prime is 67729393. The next prime is 67729423. The reversal of 67729421 is 12492776.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 55204900 + 12524521 = 7430^2 + 3539^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-67729421 is a prime.

Together with 67729423, 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 (67729423) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33864710 + 33864711.

It is an arithmetic number, because the mean of its divisors is an integer number (33864711).

Almost surely, 2^67729421 is an apocalyptic number.

It is an amenable number.

67729421 is a deficient number, since it is larger than the sum of its proper divisors (1).

67729421 is an equidigital number, since it uses as much as digits as its factorization.

67729421 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42336, while the sum is 38.

The square root of 67729421 is about 8229.7886364110. The cubic root of 67729421 is about 407.6234130071.

The spelling of 67729421 in words is "sixty-seven million, seven hundred twenty-nine thousand, four hundred twenty-one".