20721337 has 8 divisors (see below), whose sum is σ = 25503296. Its totient is φ = 16394832.

The previous prime is 20721329. The next prime is 20721353. The reversal of 20721337 is 73312702.

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 20721337 - 2³ = 20721329 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20721377) 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, 113763 + ... + 113944.

It is an arithmetic number, because the mean of its divisors is an integer number (3187912).

Almost surely, 2^20721337 is an apocalyptic number.

It is an amenable number.

20721337 is a deficient number, since it is larger than the sum of its proper divisors (4781959).

20721337 is a wasteful number, since it uses less digits than its factorization.

20721337 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 227727.

The product of its (nonzero) digits is 1764, while the sum is 25.

The square root of 20721337 is about 4552.0695293460. The cubic root of 20721337 is about 274.6666462110. Note that the first 4 decimals are identical.

The spelling of 20721337 in words is "twenty million, seven hundred twenty-one thousand, three hundred thirty-seven".