21396757 has 8 divisors (see below), whose sum is σ = 22144320. Its totient is φ = 20660640.

The previous prime is 21396743. The next prime is 21396769. The reversal of 21396757 is 75769312.

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

It is not a de Polignac number, because 21396757 - 2¹⁵ = 21363989 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 (21396257) 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 7 ways as a sum of consecutive naturals, for example, 1032 + ... + 6622.

It is an arithmetic number, because the mean of its divisors is an integer number (2768040).

Almost surely, 2^21396757 is an apocalyptic number.

It is an amenable number.

21396757 is a deficient number, since it is larger than the sum of its proper divisors (747563).

21396757 is an equidigital number, since it uses as much as digits as its factorization.

21396757 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5723.

The product of its digits is 79380, while the sum is 40.

The square root of 21396757 is about 4625.6628714164. The cubic root of 21396757 is about 277.6190847820.

The spelling of 21396757 in words is "twenty-one million, three hundred ninety-six thousand, seven hundred fifty-seven".