21989493947 has 8 divisors (see below), whose sum is σ = 22137696000. Its totient is φ = 21841395264.

The previous prime is 21989493943. The next prime is 21989493949. The reversal of 21989493947 is 74939498912.

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

It is a cyclic number.

It is not a de Polignac number, because 21989493947 - 2² = 21989493943 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21989493941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 427679 + ... + 476327.

It is an arithmetic number, because the mean of its divisors is an integer number (2767212000).

Almost surely, 2^21989493947 is an apocalyptic number.

21989493947 is a deficient number, since it is larger than the sum of its proper divisors (148202053).

21989493947 is a wasteful number, since it uses less digits than its factorization.

21989493947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51685.

The product of its digits is 35271936, while the sum is 65.

The spelling of 21989493947 in words is "twenty-one billion, nine hundred eighty-nine million, four hundred ninety-three thousand, nine hundred forty-seven".