20717491 has 4 divisors (see below), whose sum is σ = 21057184. Its totient is φ = 20377800.

The previous prime is 20717483. The next prime is 20717497. The reversal of 20717491 is 19471702.

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 20717491 - 2³ = 20717483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20717497) 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, 169755 + ... + 169876.

It is an arithmetic number, because the mean of its divisors is an integer number (5264296).

Almost surely, 2^20717491 is an apocalyptic number.

20717491 is a deficient number, since it is larger than the sum of its proper divisors (339693).

20717491 is an equidigital number, since it uses as much as digits as its factorization.

20717491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 339692.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 20717491 is about 4551.6470645251. The cubic root of 20717491 is about 274.6496519202.

The spelling of 20717491 in words is "twenty million, seven hundred seventeen thousand, four hundred ninety-one".