21743513 has 4 divisors (see below), whose sum is σ = 23720208. Its totient is φ = 19766820.

The previous prime is 21743507. The next prime is 21743521. The reversal of 21743513 is 31534712.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21743513 - 2⁴ = 21743497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21743213) 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, 988331 + ... + 988352.

It is an arithmetic number, because the mean of its divisors is an integer number (5930052).

Almost surely, 2^21743513 is an apocalyptic number.

It is an amenable number.

21743513 is a deficient number, since it is larger than the sum of its proper divisors (1976695).

21743513 is a wasteful number, since it uses less digits than its factorization.

21743513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1976694.

The product of its digits is 2520, while the sum is 26.

The square root of 21743513 is about 4662.9939952781. The cubic root of 21743513 is about 279.1107545361.

The spelling of 21743513 in words is "twenty-one million, seven hundred forty-three thousand, five hundred thirteen".