20861187 has 8 divisors (see below), whose sum is σ = 28230336. Its totient is φ = 13699752.

The previous prime is 20861173. The next prime is 20861209. The reversal of 20861187 is 78116802.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 20861187 - 2¹⁰ = 20860163 is a prime.

It is not an unprimeable number, because it can be changed into a prime (20861167) 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 7 ways as a sum of consecutive naturals, for example, 51693 + ... + 52094.

It is an arithmetic number, because the mean of its divisors is an integer number (3528792).

Almost surely, 2^20861187 is an apocalyptic number.

20861187 is a deficient number, since it is larger than the sum of its proper divisors (7369149).

20861187 is a wasteful number, since it uses less digits than its factorization.

20861187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 103857.

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 20861187 is about 4567.4048430153. The cubic root of 20861187 is about 275.2831771729.

Adding to 20861187 its reverse (78116802), we get a palindrome (98977989).

The spelling of 20861187 in words is "twenty million, eight hundred sixty-one thousand, one hundred eighty-seven".