71721761 has 4 divisors (see below), whose sum is σ = 72001092. Its totient is φ = 71442432.

The previous prime is 71721743. The next prime is 71721763. The reversal of 71721761 is 16712717.

It is a happy number.

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 71081761 + 640000 = 8431^2 + 800^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-71721761 is a prime.

It is a super-2 number, since 2×71721761² = 10288022001882242, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (71721763) 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, 139280 + ... + 139793.

It is an arithmetic number, because the mean of its divisors is an integer number (18000273).

Almost surely, 2^71721761 is an apocalyptic number.

It is an amenable number.

71721761 is a deficient number, since it is larger than the sum of its proper divisors (279331).

71721761 is a wasteful number, since it uses less digits than its factorization.

71721761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 279330.

The product of its digits is 4116, while the sum is 32.

The square root of 71721761 is about 8468.8701135393. The cubic root of 71721761 is about 415.4801835233.

The spelling of 71721761 in words is "seventy-one million, seven hundred twenty-one thousand, seven hundred sixty-one".