20749217 has 4 divisors (see below), whose sum is σ = 20766720. Its totient is φ = 20731716.

The previous prime is 20749213. The next prime is 20749229. The reversal of 20749217 is 71294702.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 20749217 - 2² = 20749213 is a prime.

It is a super-2 number, since 2×20749217² = 861060012226178, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20749213) 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 3 ways as a sum of consecutive naturals, for example, 6833 + ... + 9390.

It is an arithmetic number, because the mean of its divisors is an integer number (5191680).

Almost surely, 2^20749217 is an apocalyptic number.

It is an amenable number.

20749217 is a deficient number, since it is larger than the sum of its proper divisors (17503).

20749217 is a wasteful number, since it uses less digits than its factorization.

20749217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17502.

The product of its (nonzero) digits is 7056, while the sum is 32.

The square root of 20749217 is about 4555.1308433458. The cubic root of 20749217 is about 274.7897765259.

The spelling of 20749217 in words is "twenty million, seven hundred forty-nine thousand, two hundred seventeen".