20981986 has 8 divisors (see below), whose sum is σ = 31499244. Its totient is φ = 10482240.

The previous prime is 20981971. The next prime is 20981999. The reversal of 20981986 is 68918902.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20115225 + 866761 = 4485^2 + 931^2 .

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 795 + ... + 6526.

Almost surely, 2^20981986 is an apocalyptic number.

20981986 is a deficient number, since it is larger than the sum of its proper divisors (10517258).

20981986 is a wasteful number, since it uses less digits than its factorization.

20981986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8756.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 20981986 is about 4580.6097847339. The cubic root of 20981986 is about 275.8135073560.

The spelling of 20981986 in words is "twenty million, nine hundred eighty-one thousand, nine hundred eighty-six".