21653701 has 4 divisors (see below), whose sum is σ = 21669804. Its totient is φ = 21637600.

The previous prime is 21653677. The next prime is 21653707. The reversal of 21653701 is 10735612.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2722500 + 18931201 = 1650^2 + 4351^2 .

It is a cyclic number.

It is not a de Polignac number, because 21653701 - 2⁵ = 21653669 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 (21653707) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5830 + ... + 8791.

It is an arithmetic number, because the mean of its divisors is an integer number (5417451).

Almost surely, 2^21653701 is an apocalyptic number.

It is an amenable number.

21653701 is a deficient number, since it is larger than the sum of its proper divisors (16103).

21653701 is a wasteful number, since it uses less digits than its factorization.

21653701 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16102.

The product of its (nonzero) digits is 1260, while the sum is 25.

The square root of 21653701 is about 4653.3537368225. The cubic root of 21653701 is about 278.7259334260.

The spelling of 21653701 in words is "twenty-one million, six hundred fifty-three thousand, seven hundred one".