21820947 has 8 divisors (see below), whose sum is σ = 29241600. Its totient is φ = 14473800.

The previous prime is 21820937. The next prime is 21820957. The reversal of 21820947 is 74902812.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21820937) and next prime (21820957).

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

It is not a de Polignac number, because 21820947 - 2⁸ = 21820691 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21820937) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17679 + ... + 18872.

It is an arithmetic number, because the mean of its divisors is an integer number (3655200).

Almost surely, 2^21820947 is an apocalyptic number.

21820947 is a deficient number, since it is larger than the sum of its proper divisors (7420653).

21820947 is a wasteful number, since it uses less digits than its factorization.

21820947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36753.

The product of its (nonzero) digits is 8064, while the sum is 33.

The square root of 21820947 is about 4671.2896506211. The cubic root of 21820947 is about 279.4416893579.

The spelling of 21820947 in words is "twenty-one million, eight hundred twenty thousand, nine hundred forty-seven".