21305477 has 8 divisors (see below), whose sum is σ = 21545472. Its totient is φ = 21067200.

The previous prime is 21305461. The next prime is 21305483. The reversal of 21305477 is 77450312.

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

It is a cyclic number.

It is not a de Polignac number, because 21305477 - 2⁴ = 21305461 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305497) 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, 63053 + ... + 63389.

It is an arithmetic number, because the mean of its divisors is an integer number (2693184).

Almost surely, 2^21305477 is an apocalyptic number.

It is an amenable number.

21305477 is a deficient number, since it is larger than the sum of its proper divisors (239995).

21305477 is a wasteful number, since it uses less digits than its factorization.

21305477 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 859.

The product of its (nonzero) digits is 5880, while the sum is 29.

The square root of 21305477 is about 4615.7856319374. The cubic root of 21305477 is about 277.2237415176.

Adding to 21305477 its reverse (77450312), we get a palindrome (98755789).

The spelling of 21305477 in words is "twenty-one million, three hundred five thousand, four hundred seventy-seven".