87971209 has 4 divisors (see below), whose sum is σ = 93146004. Its totient is φ = 82796416.

The previous prime is 87971203. The next prime is 87971309. The reversal of 87971209 is 90217978.

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 59721984 + 28249225 = 7728^2 + 5315^2 .

It is a cyclic number.

It is not a de Polignac number, because 87971209 - 2²⁵ = 54416777 is a prime.

It is a super-2 number, since 2×87971209² = 15477867225843362, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (87971203) 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, 2587372 + ... + 2587405.

It is an arithmetic number, because the mean of its divisors is an integer number (23286501).

Almost surely, 2^87971209 is an apocalyptic number.

It is an amenable number.

87971209 is a deficient number, since it is larger than the sum of its proper divisors (5174795).

87971209 is a wasteful number, since it uses less digits than its factorization.

87971209 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5174794.

The product of its (nonzero) digits is 63504, while the sum is 43.

The square root of 87971209 is about 9379.2968286541. The cubic root of 87971209 is about 444.7475047843.

The spelling of 87971209 in words is "eighty-seven million, nine hundred seventy-one thousand, two hundred nine".