21947507 has 2 divisors, whose sum is σ = 21947508. Its totient is φ = 21947506.

The previous prime is 21947503. The next prime is 21947521. The reversal of 21947507 is 70574912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21947507 - 2² = 21947503 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21947503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973753 + 10973754.

It is an arithmetic number, because the mean of its divisors is an integer number (10973754).

Almost surely, 2^21947507 is an apocalyptic number.

21947507 is a deficient number, since it is larger than the sum of its proper divisors (1).

21947507 is an equidigital number, since it uses as much as digits as its factorization.

21947507 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 21947507 is about 4684.8166452915. The cubic root of 21947507 is about 279.9808958054.

The spelling of 21947507 in words is "twenty-one million, nine hundred forty-seven thousand, five hundred seven".