21740013 has 6 divisors (see below), whose sum is σ = 31402254. Its totient is φ = 14493336.

The previous prime is 21740011. The next prime is 21740023. The reversal of 21740013 is 31004712.

It can be written as a sum of positive squares in only one way, i.e., 13972644 + 7767369 = 3738^2 + 2787^2 .

It is not a de Polignac number, because 21740013 - 2¹ = 21740011 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740011) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1207770 + ... + 1207787.

It is an arithmetic number, because the mean of its divisors is an integer number (5233709).

Almost surely, 2^21740013 is an apocalyptic number.

It is an amenable number.

21740013 is a deficient number, since it is larger than the sum of its proper divisors (9662241).

21740013 is a wasteful number, since it uses less digits than its factorization.

21740013 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2415563 (or 2415560 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 18.

The square root of 21740013 is about 4662.6186848165. The cubic root of 21740013 is about 279.0957778077.

Adding to 21740013 its reverse (31004712), we get a palindrome (52744725).

The spelling of 21740013 in words is "twenty-one million, seven hundred forty thousand, thirteen".