21212021986 has 8 divisors (see below), whose sum is σ = 32915206620. Its totient is φ = 10240286448.

The previous prime is 21212021959. The next prime is 21212022019. The reversal of 21212021986 is 68912021212.

It can be written as a sum of positive squares in 2 ways, for example, as 18261468225 + 2950553761 = 135135^2 + 54319^2 .

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, 182862201 + ... + 182862316.

Almost surely, 2^21212021986 is an apocalyptic number.

21212021986 is a deficient number, since it is larger than the sum of its proper divisors (11703184634).

21212021986 is a wasteful number, since it uses less digits than its factorization.

21212021986 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365724548.

The product of its (nonzero) digits is 6912, while the sum is 34.

The spelling of 21212021986 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, nine hundred eighty-six".