21475487 has 4 divisors (see below), whose sum is σ = 23427816. Its totient is φ = 19523160.

The previous prime is 21475459. The next prime is 21475499. The reversal of 21475487 is 78457412.

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 21475487 - 2⁸ = 21475231 is a prime.

It is a super-2 number, since 2×21475487² = 922393083774338, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21475487.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21475417) 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, 976148 + ... + 976169.

It is an arithmetic number, because the mean of its divisors is an integer number (5856954).

Almost surely, 2^21475487 is an apocalyptic number.

21475487 is a deficient number, since it is larger than the sum of its proper divisors (1952329).

21475487 is a wasteful number, since it uses less digits than its factorization.

21475487 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1952328.

The product of its digits is 62720, while the sum is 38.

The square root of 21475487 is about 4634.1651891144. The cubic root of 21475487 is about 277.9591705474.

The spelling of 21475487 in words is "twenty-one million, four hundred seventy-five thousand, four hundred eighty-seven".