87721381 has 8 divisors (see below), whose sum is σ = 95827104. Its totient is φ = 79637520.

The previous prime is 87721367. The next prime is 87721391. The reversal of 87721381 is 18312778.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 87721381 - 2⁹ = 87720869 is a prime.

It is a super-2 number, since 2×87721381² = 15390081369094322, 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 87721381.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87721301) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3591 + ... + 13723.

It is an arithmetic number, because the mean of its divisors is an integer number (11978388).

Almost surely, 2^87721381 is an apocalyptic number.

It is an amenable number.

87721381 is a deficient number, since it is larger than the sum of its proper divisors (8105723).

87721381 is a wasteful number, since it uses less digits than its factorization.

87721381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10931.

The product of its digits is 18816, while the sum is 37.

The square root of 87721381 is about 9365.9693038147. The cubic root of 87721381 is about 444.3260952219.

It can be divided in two parts, 8772 and 1381, that added together give a triangular number (10153 = T₁₄₂).

The spelling of 87721381 in words is "eighty-seven million, seven hundred twenty-one thousand, three hundred eighty-one".