21047071 has 4 divisors (see below), whose sum is σ = 22285152. Its totient is φ = 19808992.

The previous prime is 21047051. The next prime is 21047077. The reversal of 21047071 is 17074012.

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 21047071 - 2¹³ = 21038879 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 (21047077) 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, 619015 + ... + 619048.

It is an arithmetic number, because the mean of its divisors is an integer number (5571288).

Almost surely, 2^21047071 is an apocalyptic number.

21047071 is a deficient number, since it is larger than the sum of its proper divisors (1238081).

21047071 is a wasteful number, since it uses less digits than its factorization.

21047071 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1238080.

The product of its (nonzero) digits is 392, while the sum is 22.

The square root of 21047071 is about 4587.7086873515. The cubic root of 21047071 is about 276.0983992422.

The spelling of 21047071 in words is "twenty-one million, forty-seven thousand, seventy-one".