21577947 has 8 divisors (see below), whose sum is σ = 30463056. Its totient is φ = 13539072.

The previous prime is 21577937. The next prime is 21577949. The reversal of 21577947 is 74977512.

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

It is not a de Polignac number, because 21577947 - 2⁸ = 21577691 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21577899 and 21577908.

It is not an unprimeable number, because it can be changed into a prime (21577949) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 211498 + ... + 211599.

It is an arithmetic number, because the mean of its divisors is an integer number (3807882).

Almost surely, 2^21577947 is an apocalyptic number.

21577947 is a deficient number, since it is larger than the sum of its proper divisors (8885109).

21577947 is a wasteful number, since it uses less digits than its factorization.

21577947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423117.

The product of its digits is 123480, while the sum is 42.

The square root of 21577947 is about 4645.2068845209. The cubic root of 21577947 is about 278.4005190777.

The spelling of 21577947 in words is "twenty-one million, five hundred seventy-seven thousand, nine hundred forty-seven".