21137709 has 8 divisors (see below), whose sum is σ = 29667040. Its totient is φ = 13350096.

The previous prime is 21137707. The next prime is 21137719. The reversal of 21137709 is 90773112.

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

It is not a de Polignac number, because 21137709 - 2¹ = 21137707 is a prime.

It is a super-3 number, since 3×21137709³ (a number of 23 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21137707) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 185362 + ... + 185475.

It is an arithmetic number, because the mean of its divisors is an integer number (3708380).

Almost surely, 2^21137709 is an apocalyptic number.

It is an amenable number.

21137709 is a deficient number, since it is larger than the sum of its proper divisors (8529331).

21137709 is a wasteful number, since it uses less digits than its factorization.

21137709 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 370859.

The product of its (nonzero) digits is 2646, while the sum is 30.

The square root of 21137709 is about 4597.5764267710. The cubic root of 21137709 is about 276.4941656252.

The spelling of 21137709 in words is "twenty-one million, one hundred thirty-seven thousand, seven hundred nine".