21530477 has 4 divisors (see below), whose sum is σ = 22663680. Its totient is φ = 20397276.

The previous prime is 21530471. The next prime is 21530489. The reversal of 21530477 is 77403512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21530477 - 2⁶ = 21530413 is a prime.

It is a super-2 number, since 2×21530477² = 927122879695058, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21530471) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 566573 + ... + 566610.

It is an arithmetic number, because the mean of its divisors is an integer number (5665920).

Almost surely, 2^21530477 is an apocalyptic number.

It is an amenable number.

21530477 is a deficient number, since it is larger than the sum of its proper divisors (1133203).

21530477 is a wasteful number, since it uses less digits than its factorization.

21530477 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1133202.

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

The square root of 21530477 is about 4640.0945033480. The cubic root of 21530477 is about 278.1962151852.

Adding to 21530477 its reverse (77403512), we get a palindrome (98933989).

The spelling of 21530477 in words is "twenty-one million, five hundred thirty thousand, four hundred seventy-seven".