20931287 has 16 divisors (see below), whose sum is σ = 23184000. Its totient is φ = 18779904.

The previous prime is 20931263. The next prime is 20931289. The reversal of 20931287 is 78213902.

It is not a de Polignac number, because 20931287 - 2⁶ = 20931223 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20931289) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 91289 + ... + 91517.

It is an arithmetic number, because the mean of its divisors is an integer number (1449000).

Almost surely, 2^20931287 is an apocalyptic number.

20931287 is a deficient number, since it is larger than the sum of its proper divisors (2252713).

20931287 is a wasteful number, since it uses less digits than its factorization.

20931287 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 410.

The product of its (nonzero) digits is 6048, while the sum is 32.

The square root of 20931287 is about 4575.0723491547. The cubic root of 20931287 is about 275.5911777990.

The spelling of 20931287 in words is "twenty million, nine hundred thirty-one thousand, two hundred eighty-seven".