21356047 has 2 divisors, whose sum is σ = 21356048. Its totient is φ = 21356046.

The previous prime is 21356003. The next prime is 21356051. The reversal of 21356047 is 74065312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21356047 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21356347) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678023 + 10678024.

It is an arithmetic number, because the mean of its divisors is an integer number (10678024).

Almost surely, 2^21356047 is an apocalyptic number.

21356047 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356047 is an equidigital number, since it uses as much as digits as its factorization.

21356047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21356047 is about 4621.2603259284. The cubic root of 21356047 is about 277.4429046835.

The spelling of 21356047 in words is "twenty-one million, three hundred fifty-six thousand, forty-seven".