21730653 has 32 divisors (see below), whose sum is σ = 38400000. Its totient is φ = 11875248.

The previous prime is 21730649. The next prime is 21730663. The reversal of 21730653 is 35603712.

It is a happy number.

21730653 is a `hidden beast` number, since 2 + 1 + 7 + 3 + 0 + 653 = 666.

It is not a de Polignac number, because 21730653 - 2² = 21730649 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730663) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1848 + ... + 6846.

It is an arithmetic number, because the mean of its divisors is an integer number (1200000).

Almost surely, 2^21730653 is an apocalyptic number.

21730653 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21730653 is a deficient number, since it is larger than the sum of its proper divisors (16669347).

21730653 is a wasteful number, since it uses less digits than its factorization.

21730653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5038 (or 5032 counting only the distinct ones).

The product of its (nonzero) digits is 3780, while the sum is 27.

The square root of 21730653 is about 4661.6148489552. The cubic root of 21730653 is about 279.0557178581.

The spelling of 21730653 in words is "twenty-one million, seven hundred thirty thousand, six hundred fifty-three".