21470087 has 4 divisors (see below), whose sum is σ = 21560160. Its totient is φ = 21380016.

The previous prime is 21470081. The next prime is 21470123. The reversal of 21470087 is 78007412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21470087 - 2¹⁴ = 21453703 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 (21470081) 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, 44678 + ... + 45155.

It is an arithmetic number, because the mean of its divisors is an integer number (5390040).

Almost surely, 2^21470087 is an apocalyptic number.

21470087 is a deficient number, since it is larger than the sum of its proper divisors (90073).

21470087 is an equidigital number, since it uses as much as digits as its factorization.

21470087 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 90072.

The product of its (nonzero) digits is 3136, while the sum is 29.

The square root of 21470087 is about 4633.5825232751. The cubic root of 21470087 is about 277.9358710316.

Adding to 21470087 its reverse (78007412), we get a palindrome (99477499).

The spelling of 21470087 in words is "twenty-one million, four hundred seventy thousand, eighty-seven".