87821913 has 16 divisors (see below), whose sum is σ = 119520000. Its totient is φ = 57343440.

The previous prime is 87821911. The next prime is 87821917. The reversal of 87821913 is 31912878.

It is not a de Polignac number, because 87821913 - 2¹ = 87821911 is a prime.

It is not an unprimeable number, because it can be changed into a prime (87821911) 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 15 ways as a sum of consecutive naturals, for example, 57838 + ... + 59336.

It is an arithmetic number, because the mean of its divisors is an integer number (7470000).

Almost surely, 2^87821913 is an apocalyptic number.

It is an amenable number.

87821913 is a deficient number, since it is larger than the sum of its proper divisors (31698087).

87821913 is a wasteful number, since it uses less digits than its factorization.

87821913 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1892.

The product of its digits is 24192, while the sum is 39.

The square root of 87821913 is about 9371.3346434753. The cubic root of 87821913 is about 444.4957685567.

It can be divided in two parts, 878 and 21913, that added together give a triangular number (22791 = T₂₁₃).

The spelling of 87821913 in words is "eighty-seven million, eight hundred twenty-one thousand, nine hundred thirteen".