21849947 has 16 divisors (see below), whose sum is σ = 27297792. Its totient is φ = 17055360.

The previous prime is 21849941. The next prime is 21849979. The reversal of 21849947 is 74994812.

It is not a de Polignac number, because 21849947 - 2¹⁰ = 21848923 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21849898 and 21849907.

It is not an unprimeable number, because it can be changed into a prime (21849941) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 728 + ... + 6650.

It is an arithmetic number, because the mean of its divisors is an integer number (1706112).

Almost surely, 2^21849947 is an apocalyptic number.

21849947 is a deficient number, since it is larger than the sum of its proper divisors (5447845).

21849947 is a wasteful number, since it uses less digits than its factorization.

21849947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5978.

The product of its digits is 145152, while the sum is 44.

The square root of 21849947 is about 4674.3926878259. The cubic root of 21849947 is about 279.5654270621.

The spelling of 21849947 in words is "twenty-one million, eight hundred forty-nine thousand, nine hundred forty-seven".