21442047 has 12 divisors (see below), whose sum is σ = 31425240. Its totient is φ = 12994960.

The previous prime is 21442037. The next prime is 21442063. The reversal of 21442047 is 74024412.

It is not a de Polignac number, because 21442047 - 2⁷ = 21441919 is a prime.

It is a super-2 number, since 2×21442047² = 919522759100418, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21442037) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 29172 + ... + 29897.

It is an arithmetic number, because the mean of its divisors is an integer number (2618770).

Almost surely, 2^21442047 is an apocalyptic number.

21442047 is a deficient number, since it is larger than the sum of its proper divisors (9983193).

21442047 is a wasteful number, since it uses less digits than its factorization.

21442047 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59094 (or 59083 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 24.

The square root of 21442047 is about 4630.5557981737. Note that the first 3 decimals coincide. The cubic root of 21442047 is about 277.8148232844.

Adding to 21442047 its reverse (74024412), we get a palindrome (95466459).

The spelling of 21442047 in words is "twenty-one million, four hundred forty-two thousand, forty-seven".