21651211989 has 48 divisors (see below), whose sum is σ = 35625567744. Its totient is φ = 12542560800.

The previous prime is 21651211979. The next prime is 21651211991. The reversal of 21651211989 is 98911215612.

21651211989 is a `hidden beast` number, since 2 + 16 + 512 + 119 + 8 + 9 = 666.

It is not a de Polignac number, because 21651211989 - 2⁴ = 21651211973 is a prime.

It is a super-2 number, since 2×21651211989² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21651211909) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4613134 + ... + 4617824.

It is an arithmetic number, because the mean of its divisors is an integer number (742199328).

Almost surely, 2^21651211989 is an apocalyptic number.

It is an amenable number.

21651211989 is a deficient number, since it is larger than the sum of its proper divisors (13974355755).

21651211989 is a wasteful number, since it uses less digits than its factorization.

21651211989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6758 (or 6755 counting only the distinct ones).

The product of its digits is 77760, while the sum is 45.

The spelling of 21651211989 in words is "twenty-one billion, six hundred fifty-one million, two hundred eleven thousand, nine hundred eighty-nine".