71087821 has 4 divisors (see below), whose sum is σ = 81243232. Its totient is φ = 60932412.

The previous prime is 71087813. The next prime is 71087833. The reversal of 71087821 is 12878017.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 71087821 - 2³ = 71087813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71087801) 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, 5077695 + ... + 5077708.

It is an arithmetic number, because the mean of its divisors is an integer number (20310808).

Almost surely, 2^71087821 is an apocalyptic number.

It is an amenable number.

71087821 is a deficient number, since it is larger than the sum of its proper divisors (10155411).

71087821 is a wasteful number, since it uses less digits than its factorization.

71087821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10155410.

The product of its (nonzero) digits is 6272, while the sum is 34.

The square root of 71087821 is about 8431.3593803135. The cubic root of 71087821 is about 414.2524326528.

The spelling of 71087821 in words is "seventy-one million, eighty-seven thousand, eight hundred twenty-one".