67221521 has 2 divisors, whose sum is σ = 67221522. Its totient is φ = 67221520.

The previous prime is 67221493. The next prime is 67221523. The reversal of 67221521 is 12512276.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 59598400 + 7623121 = 7720^2 + 2761^2 .

It is a cyclic number.

It is not a de Polignac number, because 67221521 - 2⁶ = 67221457 is a prime.

Together with 67221523, 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 (67221523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 33610760 + 33610761.

It is an arithmetic number, because the mean of its divisors is an integer number (33610761).

Almost surely, 2^67221521 is an apocalyptic number.

It is an amenable number.

67221521 is a deficient number, since it is larger than the sum of its proper divisors (1).

67221521 is an equidigital number, since it uses as much as digits as its factorization.

67221521 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1680, while the sum is 26.

The square root of 67221521 is about 8198.8731542816. The cubic root of 67221521 is about 406.6019386215.

Adding to 67221521 its reverse (12512276), we get a palindrome (79733797).

The spelling of 67221521 in words is "sixty-seven million, two hundred twenty-one thousand, five hundred twenty-one".