21455047 has 4 divisors (see below), whose sum is σ = 22584280. Its totient is φ = 20325816.

The previous prime is 21455039. The next prime is 21455051. The reversal of 21455047 is 74055412.

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 21455047 - 2³ = 21455039 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 (21455087) 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, 564588 + ... + 564625.

It is an arithmetic number, because the mean of its divisors is an integer number (5646070).

Almost surely, 2^21455047 is an apocalyptic number.

21455047 is a deficient number, since it is larger than the sum of its proper divisors (1129233).

21455047 is a wasteful number, since it uses less digits than its factorization.

21455047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1129232.

The product of its (nonzero) digits is 5600, while the sum is 28.

The square root of 21455047 is about 4631.9593046572. The cubic root of 21455047 is about 277.8709569652.

The spelling of 21455047 in words is "twenty-one million, four hundred fifty-five thousand, forty-seven".