87670021 has 4 divisors (see below), whose sum is σ = 87918732. Its totient is φ = 87421312.

The previous prime is 87670001. The next prime is 87670027. The reversal of 87670021 is 12007678.

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 21068100 + 66601921 = 4590^2 + 8161^2 .

It is a cyclic number.

It is not a de Polignac number, because 87670021 - 2¹³ = 87661829 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (87670027) 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, 123826 + ... + 124531.

It is an arithmetic number, because the mean of its divisors is an integer number (21979683).

Almost surely, 2^87670021 is an apocalyptic number.

It is an amenable number.

87670021 is a deficient number, since it is larger than the sum of its proper divisors (248711).

87670021 is a wasteful number, since it uses less digits than its factorization.

87670021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 248710.

The product of its (nonzero) digits is 4704, while the sum is 31.

The square root of 87670021 is about 9363.2270612220. The cubic root of 87670021 is about 444.2393621161.

Adding to 87670021 its reverse (12007678), we get a palindrome (99677699).

The spelling of 87670021 in words is "eighty-seven million, six hundred seventy thousand, twenty-one".