67721261 has 4 divisors (see below), whose sum is σ = 67737852. Its totient is φ = 67704672.

The previous prime is 67721233. The next prime is 67721273. The reversal of 67721261 is 16212776.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 58049161 + 9672100 = 7619^2 + 3110^2 .

It is a cyclic number.

It is not a de Polignac number, because 67721261 - 2⁶ = 67721197 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (67721231) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2585 + ... + 11921.

It is an arithmetic number, because the mean of its divisors is an integer number (16934463).

Almost surely, 2^67721261 is an apocalyptic number.

It is an amenable number.

67721261 is a deficient number, since it is larger than the sum of its proper divisors (16591).

67721261 is an equidigital number, since it uses as much as digits as its factorization.

67721261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16590.

The product of its digits is 7056, while the sum is 32.

The square root of 67721261 is about 8229.2928614797. The cubic root of 67721261 is about 407.6070422750.

The spelling of 67721261 in words is "sixty-seven million, seven hundred twenty-one thousand, two hundred sixty-one".