21075947 has 2 divisors, whose sum is σ = 21075948. Its totient is φ = 21075946.

The previous prime is 21075931. The next prime is 21075979. The reversal of 21075947 is 74957012.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21075947 - 2⁴ = 21075931 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21075907) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10537973 + 10537974.

It is an arithmetic number, because the mean of its divisors is an integer number (10537974).

Almost surely, 2^21075947 is an apocalyptic number.

21075947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21075947 is an equidigital number, since it uses as much as digits as its factorization.

21075947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 17640, while the sum is 35.

The square root of 21075947 is about 4590.8547134493. The cubic root of 21075947 is about 276.2246080003.

It can be divided in two parts, 21075 and 947, that added together give a palindrome (22022).

The spelling of 21075947 in words is "twenty-one million, seventy-five thousand, nine hundred forty-seven".