21022947 has 12 divisors (see below), whose sum is σ = 33127224. Its totient is φ = 12741120.

The previous prime is 21022921. The next prime is 21022997. The reversal of 21022947 is 74922012.

It is not a de Polignac number, because 21022947 - 2¹⁴ = 21006563 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21022947.

It is not an unprimeable number, because it can be changed into a prime (21022997) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 106078 + ... + 106275.

It is an arithmetic number, because the mean of its divisors is an integer number (2760602).

Almost surely, 2^21022947 is an apocalyptic number.

21022947 is a deficient number, since it is larger than the sum of its proper divisors (12104277).

21022947 is a wasteful number, since it uses less digits than its factorization.

21022947 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212370 (or 212367 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 27.

The square root of 21022947 is about 4585.0787343294. The cubic root of 21022947 is about 275.9928715865.

Adding to 21022947 its reverse (74922012), we get a palindrome (95944959).

It can be divided in two parts, 210229 and 47, that added together give a triangular number (210276 = T₆₄₈).

The spelling of 21022947 in words is "twenty-one million, twenty-two thousand, nine hundred forty-seven".