21740057 has 4 divisors (see below), whose sum is σ = 22037940. Its totient is φ = 21442176.

The previous prime is 21740051. The next prime is 21740063. The reversal of 21740057 is 75004712.

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

It is an interprime number because it is at equal distance from previous prime (21740051) and next prime (21740063).

It can be written as a sum of positive squares in 2 ways, for example, as 18284176 + 3455881 = 4276^2 + 1859^2 .

It is a cyclic number.

It is not a de Polignac number, because 21740057 - 2⁸ = 21739801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21740051) 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 3 ways as a sum of consecutive naturals, for example, 148832 + ... + 148977.

It is an arithmetic number, because the mean of its divisors is an integer number (5509485).

Almost surely, 2^21740057 is an apocalyptic number.

It is an amenable number.

21740057 is a deficient number, since it is larger than the sum of its proper divisors (297883).

21740057 is an equidigital number, since it uses as much as digits as its factorization.

21740057 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297882.

The product of its (nonzero) digits is 1960, while the sum is 26.

The square root of 21740057 is about 4662.6234031927. The cubic root of 21740057 is about 279.0959660966.

Adding to 21740057 its reverse (75004712), we get a palindrome (96744769).

The spelling of 21740057 in words is "twenty-one million, seven hundred forty thousand, fifty-seven".