21742055 has 4 divisors (see below), whose sum is σ = 26090472. Its totient is φ = 17393640.

The previous prime is 21742043. The next prime is 21742087. The reversal of 21742055 is 55024712.

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

It is not a de Polignac number, because 21742055 - 2⁸ = 21741799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2174201 + ... + 2174210.

It is an arithmetic number, because the mean of its divisors is an integer number (6522618).

Almost surely, 2^21742055 is an apocalyptic number.

21742055 is a deficient number, since it is larger than the sum of its proper divisors (4348417).

21742055 is an equidigital number, since it uses as much as digits as its factorization.

21742055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4348416.

The product of its (nonzero) digits is 2800, while the sum is 26.

The square root of 21742055 is about 4662.8376553339. The cubic root of 21742055 is about 279.1045158543.

Adding to 21742055 its reverse (55024712), we get a palindrome (76766767).

The spelling of 21742055 in words is "twenty-one million, seven hundred forty-two thousand, fifty-five".