21742073 has 4 divisors (see below), whose sum is σ = 21845328. Its totient is φ = 21638820.

The previous prime is 21742043. The next prime is 21742087. The reversal of 21742073 is 37024712.

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 21742073 - 2⁶ = 21742009 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21742003) 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, 51311 + ... + 51732.

It is an arithmetic number, because the mean of its divisors is an integer number (5461332).

Almost surely, 2^21742073 is an apocalyptic number.

It is an amenable number.

21742073 is a deficient number, since it is larger than the sum of its proper divisors (103255).

21742073 is a wasteful number, since it uses less digits than its factorization.

21742073 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 103254.

The product of its (nonzero) digits is 2352, while the sum is 26.

The square root of 21742073 is about 4662.8395854887. The cubic root of 21742073 is about 279.1045928767.

Adding to 21742073 its reverse (37024712), we get a palindrome (58766785).

The spelling of 21742073 in words is "twenty-one million, seven hundred forty-two thousand, seventy-three".