21293947 has 2 divisors, whose sum is σ = 21293948. Its totient is φ = 21293946.

The previous prime is 21293939. The next prime is 21293953. The reversal of 21293947 is 74939212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21293947 - 2³ = 21293939 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21293957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10646973 + 10646974.

It is an arithmetic number, because the mean of its divisors is an integer number (10646974).

Almost surely, 2^21293947 is an apocalyptic number.

21293947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21293947 is an equidigital number, since it uses as much as digits as its factorization.

21293947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 37.

The square root of 21293947 is about 4614.5364880993. The cubic root of 21293947 is about 277.1737236041.

The spelling of 21293947 in words is "twenty-one million, two hundred ninety-three thousand, nine hundred forty-seven".