21166311651 has 8 divisors (see below), whose sum is σ = 28222439424. Its totient is φ = 14110529160.

The previous prime is 21166311643. The next prime is 21166311653. The reversal of 21166311651 is 15611366112.

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

It is not a de Polignac number, because 21166311651 - 2³ = 21166311643 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21166311653) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 146190 + ... + 252396.

It is an arithmetic number, because the mean of its divisors is an integer number (3527804928).

Almost surely, 2^21166311651 is an apocalyptic number.

21166311651 is a deficient number, since it is larger than the sum of its proper divisors (7056127773).

21166311651 is a wasteful number, since it uses less digits than its factorization.

21166311651 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 172641.

The product of its digits is 6480, while the sum is 33.

Adding to 21166311651 its reverse (15611366112), we get a palindrome (36777677763).

The spelling of 21166311651 in words is "twenty-one billion, one hundred sixty-six million, three hundred eleven thousand, six hundred fifty-one".