21742613 has 4 divisors (see below), whose sum is σ = 22687968. Its totient is φ = 20797260.

The previous prime is 21742603. The next prime is 21742619. The reversal of 21742613 is 31624712.

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 21742613 - 2¹⁶ = 21677077 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21742619) 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, 472643 + ... + 472688.

It is an arithmetic number, because the mean of its divisors is an integer number (5671992).

Almost surely, 2^21742613 is an apocalyptic number.

21742613 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21742613 is a deficient number, since it is larger than the sum of its proper divisors (945355).

21742613 is an equidigital number, since it uses as much as digits as its factorization.

21742613 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 945354.

The product of its digits is 2016, while the sum is 26.

The square root of 21742613 is about 4662.8974897589. The cubic root of 21742613 is about 279.1069035309.

The spelling of 21742613 in words is "twenty-one million, seven hundred forty-two thousand, six hundred thirteen".