21269947 has 2 divisors, whose sum is σ = 21269948. Its totient is φ = 21269946.

The previous prime is 21269923. The next prime is 21269953. The reversal of 21269947 is 74996212.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21269947 - 2⁷ = 21269819 is a prime.

It is not a weakly prime, because it can be changed into another prime (21269957) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10634973 + 10634974.

It is an arithmetic number, because the mean of its divisors is an integer number (10634974).

Almost surely, 2^21269947 is an apocalyptic number.

21269947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21269947 is an equidigital number, since it uses as much as digits as its factorization.

21269947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 54432, while the sum is 40.

The square root of 21269947 is about 4611.9352770827. The cubic root of 21269947 is about 277.0695520586.

The spelling of 21269947 in words is "twenty-one million, two hundred sixty-nine thousand, nine hundred forty-seven".