21740555 has 16 divisors (see below), whose sum is σ = 27039744. Its totient is φ = 16769760.

The previous prime is 21740549. The next prime is 21740557. The reversal of 21740555 is 55504712.

It is not a de Polignac number, because 21740555 - 2⁴ = 21740539 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21740557) 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 15 ways as a sum of consecutive naturals, for example, 16034 + ... + 17336.

It is an arithmetic number, because the mean of its divisors is an integer number (1689984).

Almost surely, 2^21740555 is an apocalyptic number.

21740555 is a deficient number, since it is larger than the sum of its proper divisors (5299189).

21740555 is a wasteful number, since it uses less digits than its factorization.

21740555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1426.

The product of its (nonzero) digits is 7000, while the sum is 29.

The square root of 21740555 is about 4662.6768062991. The cubic root of 21740555 is about 279.0980971663.

The spelling of 21740555 in words is "twenty-one million, seven hundred forty thousand, five hundred fifty-five".