21740642 has 32 divisors (see below), whose sum is σ = 41195520. Its totient is φ = 8358480.

The previous prime is 21740639. The next prime is 21740647. The reversal of 21740642 is 24604712.

It is not an unprimeable number, because it can be changed into a prime (21740647) 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, 11273 + ... + 13059.

It is an arithmetic number, because the mean of its divisors is an integer number (1287360).

Almost surely, 2^21740642 is an apocalyptic number.

21740642 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

21740642 is a deficient number, since it is larger than the sum of its proper divisors (19454878).

21740642 is a wasteful number, since it uses less digits than its factorization.

21740642 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1886.

The product of its (nonzero) digits is 2688, while the sum is 26.

The square root of 21740642 is about 4662.6861356947. The cubic root of 21740642 is about 279.0984694582.

The spelling of 21740642 in words is "twenty-one million, seven hundred forty thousand, six hundred forty-two".