21396139 has 4 divisors (see below), whose sum is σ = 21851424. Its totient is φ = 20940856.

The previous prime is 21396119. The next prime is 21396161. The reversal of 21396139 is 93169312.

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

It is a cyclic number.

It is not a de Polignac number, because 21396139 - 2¹⁷ = 21265067 is a prime.

It is a Duffinian number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (21396119) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 227572 + ... + 227665.

It is an arithmetic number, because the mean of its divisors is an integer number (5462856).

Almost surely, 2^21396139 is an apocalyptic number.

21396139 is a deficient number, since it is larger than the sum of its proper divisors (455285).

21396139 is an equidigital number, since it uses as much as digits as its factorization.

21396139 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 455284.

The product of its digits is 8748, while the sum is 34.

The square root of 21396139 is about 4625.5960696974. The cubic root of 21396139 is about 277.6164119432.

The spelling of 21396139 in words is "twenty-one million, three hundred ninety-six thousand, one hundred thirty-nine".