21047819 has 8 divisors (see below), whose sum is σ = 24000480. Its totient is φ = 18285696.

The previous prime is 21047813. The next prime is 21047827. The reversal of 21047819 is 91874012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21047819 - 2⁸ = 21047563 is a prime.

It is a super-2 number, since 2×21047819² = 886021369313522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21047813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 47399 + ... + 47840.

It is an arithmetic number, because the mean of its divisors is an integer number (3000060).

Almost surely, 2^21047819 is an apocalyptic number.

21047819 is a deficient number, since it is larger than the sum of its proper divisors (2952661).

21047819 is a wasteful number, since it uses less digits than its factorization.

21047819 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95269.

The product of its (nonzero) digits is 4032, while the sum is 32.

The square root of 21047819 is about 4587.7902088042. The cubic root of 21047819 is about 276.1016699927.

The spelling of 21047819 in words is "twenty-one million, forty-seven thousand, eight hundred nineteen".