21533725 has 12 divisors (see below), whose sum is σ = 26785984. Its totient is φ = 17172720.

The previous prime is 21533723. The next prime is 21533731. The reversal of 21533725 is 52733512.

It is not a de Polignac number, because 21533725 - 2¹ = 21533723 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21533693 and 21533702.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21533723) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8002 + ... + 10348.

Almost surely, 2^21533725 is an apocalyptic number.

21533725 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21533725 is a deficient number, since it is larger than the sum of its proper divisors (5252259).

21533725 is a wasteful number, since it uses less digits than its factorization.

21533725 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2724 (or 2719 counting only the distinct ones).

The product of its digits is 6300, while the sum is 28.

The square root of 21533725 is about 4640.4444830210. Note that the first 4 decimals coincide. The cubic root of 21533725 is about 278.2102036641.

The spelling of 21533725 in words is "twenty-one million, five hundred thirty-three thousand, seven hundred twenty-five".