20537491 has 4 divisors (see below), whose sum is σ = 22117312. Its totient is φ = 18957672.

The previous prime is 20537483. The next prime is 20537497. The reversal of 20537491 is 19473502.

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 20537491 - 2³ = 20537483 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20537497) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 789891 + ... + 789916.

It is an arithmetic number, because the mean of its divisors is an integer number (5529328).

Almost surely, 2^20537491 is an apocalyptic number.

20537491 is a deficient number, since it is larger than the sum of its proper divisors (1579821).

20537491 is a wasteful number, since it uses less digits than its factorization.

20537491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1579820.

The product of its (nonzero) digits is 7560, while the sum is 31.

The square root of 20537491 is about 4531.8308662173. The cubic root of 20537491 is about 273.8519232932.

The spelling of 20537491 in words is "twenty million, five hundred thirty-seven thousand, four hundred ninety-one".