20649947 has 2 divisors, whose sum is σ = 20649948. Its totient is φ = 20649946.

The previous prime is 20649931. The next prime is 20649949. The reversal of 20649947 is 74994602.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 20649947 - 2⁴ = 20649931 is a prime.

It is a super-2 number, since 2×20649947² = 852840622205618, which contains 22 as substring.

Together with 20649949, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (20649949) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10324973 + 10324974.

It is an arithmetic number, because the mean of its divisors is an integer number (10324974).

Almost surely, 2^20649947 is an apocalyptic number.

20649947 is a deficient number, since it is larger than the sum of its proper divisors (1).

20649947 is an equidigital number, since it uses as much as digits as its factorization.

20649947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 108864, while the sum is 41.

The square root of 20649947 is about 4544.2212754222. The cubic root of 20649947 is about 274.3508523398.

The spelling of 20649947 in words is "twenty million, six hundred forty-nine thousand, nine hundred forty-seven".