21713653 has 4 divisors (see below), whose sum is σ = 23383948. Its totient is φ = 20043360.

The previous prime is 21713639. The next prime is 21713669. The reversal of 21713653 is 35631712.

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 14085009 + 7628644 = 3753^2 + 2762^2 .

It is a cyclic number.

It is not a de Polignac number, because 21713653 - 2²¹ = 19616501 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 (21713603) 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, 835128 + ... + 835153.

It is an arithmetic number, because the mean of its divisors is an integer number (5845987).

Almost surely, 2^21713653 is an apocalyptic number.

It is an amenable number.

21713653 is a deficient number, since it is larger than the sum of its proper divisors (1670295).

21713653 is a wasteful number, since it uses less digits than its factorization.

21713653 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1670294.

The product of its digits is 3780, while the sum is 28.

The square root of 21713653 is about 4659.7910897378. The cubic root of 21713653 is about 278.9829299731.

It can be divided in two parts, 21713 and 653, that added together give a triangular number (22366 = T₂₁₁).

The spelling of 21713653 in words is "twenty-one million, seven hundred thirteen thousand, six hundred fifty-three".