21530775 has 24 divisors (see below), whose sum is σ = 40683904. Its totient is φ = 9842400.

The previous prime is 21530749. The next prime is 21530777. The reversal of 21530775 is 57703512.

It is not a de Polignac number, because 21530775 - 2⁶ = 21530711 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 (21530777) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19981 + ... + 21030.

Almost surely, 2^21530775 is an apocalyptic number.

21530775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21530775 is a deficient number, since it is larger than the sum of its proper divisors (19153129).

21530775 is a wasteful number, since it uses less digits than its factorization.

21530775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41031 (or 41026 counting only the distinct ones).

The product of its (nonzero) digits is 7350, while the sum is 30.

The square root of 21530775 is about 4640.1266146518. The cubic root of 21530775 is about 278.1974986695.

The spelling of 21530775 in words is "twenty-one million, five hundred thirty thousand, seven hundred seventy-five".