21413947 has 2 divisors, whose sum is σ = 21413948. Its totient is φ = 21413946.

The previous prime is 21413941. The next prime is 21413971. The reversal of 21413947 is 74931412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21413947 - 2³ = 21413939 is a prime.

It is a super-2 number, since 2×21413947² = 917114252237618, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21413941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10706973 + 10706974.

It is an arithmetic number, because the mean of its divisors is an integer number (10706974).

Almost surely, 2^21413947 is an apocalyptic number.

21413947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21413947 is an equidigital number, since it uses as much as digits as its factorization.

21413947 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6048, while the sum is 31.

The square root of 21413947 is about 4627.5206104349. The cubic root of 21413947 is about 277.6934106036.

It can be divided in two parts, 214 and 13947, that added together give a square (14161 = 119²).

The spelling of 21413947 in words is "twenty-one million, four hundred thirteen thousand, nine hundred forty-seven".