21087471 has 16 divisors (see below), whose sum is σ = 29196288. Its totient is φ = 13524000.

The previous prime is 21087457. The next prime is 21087491. The reversal of 21087471 is 17478012.

It is not a de Polignac number, because 21087471 - 2⁵ = 21087439 is a prime.

It is a super-3 number, since 3×21087471³ (a number of 23 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21087401) 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, 17746 + ... + 18896.

It is an arithmetic number, because the mean of its divisors is an integer number (1824768).

Almost surely, 2^21087471 is an apocalyptic number.

21087471 is a deficient number, since it is larger than the sum of its proper divisors (8108817).

21087471 is a wasteful number, since it uses less digits than its factorization.

21087471 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1382.

The product of its (nonzero) digits is 3136, while the sum is 30.

The square root of 21087471 is about 4592.1096459035. The cubic root of 21087471 is about 276.2749439335.

The spelling of 21087471 in words is "twenty-one million, eighty-seven thousand, four hundred seventy-one".