21740399 has 8 divisors (see below), whose sum is σ = 23063040. Its totient is φ = 20422656.

The previous prime is 21740387. The next prime is 21740417. The reversal of 21740399 is 99304712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21740399 - 2¹² = 21736303 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21740309) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12242 + ... + 13904.

It is an arithmetic number, because the mean of its divisors is an integer number (2882880).

Almost surely, 2^21740399 is an apocalyptic number.

21740399 is a deficient number, since it is larger than the sum of its proper divisors (1322641).

21740399 is a wasteful number, since it uses less digits than its factorization.

21740399 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2449.

The product of its (nonzero) digits is 13608, while the sum is 35.

The square root of 21740399 is about 4662.6600776810. The cubic root of 21740399 is about 279.0974296058.

The spelling of 21740399 in words is "twenty-one million, seven hundred forty thousand, three hundred ninety-nine".