21392747 has 2 divisors, whose sum is σ = 21392748. Its totient is φ = 21392746.

The previous prime is 21392743. The next prime is 21392773. The reversal of 21392747 is 74729312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21392747 - 2² = 21392743 is a prime.

It is not a weakly prime, because it can be changed into another prime (21392741) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10696373 + 10696374.

It is an arithmetic number, because the mean of its divisors is an integer number (10696374).

Almost surely, 2^21392747 is an apocalyptic number.

21392747 is a deficient number, since it is larger than the sum of its proper divisors (1).

21392747 is an equidigital number, since it uses as much as digits as its factorization.

21392747 is an evil number, because the sum of its binary digits is even.

The product of its digits is 21168, while the sum is 35.

The square root of 21392747 is about 4625.2293997163. The cubic root of 21392747 is about 277.6017406881.

The spelling of 21392747 in words is "twenty-one million, three hundred ninety-two thousand, seven hundred forty-seven".