21735731 has 4 divisors (see below), whose sum is σ = 21757464. Its totient is φ = 21714000.

The previous prime is 21735719. The next prime is 21735737. The reversal of 21735731 is 13753712.

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

It is a cyclic number.

It is not a de Polignac number, because 21735731 - 2¹⁰ = 21734707 is a prime.

It is a super-2 number, since 2×21735731² = 944884004208722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21735694 and 21735703.

It is not an unprimeable number, because it can be changed into a prime (21735737) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9290 + ... + 11391.

It is an arithmetic number, because the mean of its divisors is an integer number (5439366).

Almost surely, 2^21735731 is an apocalyptic number.

21735731 is a deficient number, since it is larger than the sum of its proper divisors (21733).

21735731 is a wasteful number, since it uses less digits than its factorization.

21735731 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21732.

The product of its digits is 4410, while the sum is 29.

The square root of 21735731 is about 4662.1594781818. The cubic root of 21735731 is about 279.0774526639.

The spelling of 21735731 in words is "twenty-one million, seven hundred thirty-five thousand, seven hundred thirty-one".