67721761 has 4 divisors (see below), whose sum is σ = 71705412. Its totient is φ = 63738112.

The previous prime is 67721749. The next prime is 67721767. The reversal of 67721761 is 16712776.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 45819361 + 21902400 = 6769^2 + 4680^2 .

It is a cyclic number.

It is not a de Polignac number, because 67721761 - 2¹¹ = 67719713 is a prime.

It is a super-2 number, since 2×67721761² = 9172473825882242, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 67721761.

It is not an unprimeable number, because it can be changed into a prime (67721767) 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, 1991800 + ... + 1991833.

It is an arithmetic number, because the mean of its divisors is an integer number (17926353).

Almost surely, 2^67721761 is an apocalyptic number.

It is an amenable number.

67721761 is a deficient number, since it is larger than the sum of its proper divisors (3983651).

67721761 is a wasteful number, since it uses less digits than its factorization.

67721761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3983650.

The product of its digits is 24696, while the sum is 37.

The square root of 67721761 is about 8229.3232407045. The cubic root of 67721761 is about 407.6080454214.

The spelling of 67721761 in words is "sixty-seven million, seven hundred twenty-one thousand, seven hundred sixty-one".