21352747 has 4 divisors (see below), whose sum is σ = 22995280. Its totient is φ = 19710216.

The previous prime is 21352733. The next prime is 21352781. The reversal of 21352747 is 74725312.

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 21352747 - 2⁷ = 21352619 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21352847) 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, 821247 + ... + 821272.

It is an arithmetic number, because the mean of its divisors is an integer number (5748820).

Almost surely, 2^21352747 is an apocalyptic number.

21352747 is a deficient number, since it is larger than the sum of its proper divisors (1642533).

21352747 is a wasteful number, since it uses less digits than its factorization.

21352747 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1642532.

The product of its digits is 11760, while the sum is 31.

The square root of 21352747 is about 4620.9032666785. The cubic root of 21352747 is about 277.4286135126.

The spelling of 21352747 in words is "twenty-one million, three hundred fifty-two thousand, seven hundred forty-seven".