21106991937 has 8 divisors (see below), whose sum is σ = 29798106336. Its totient is φ = 13243602752.

The previous prime is 21106991933. The next prime is 21106991959. The reversal of 21106991937 is 73919960112.

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

It is not a de Polignac number, because 21106991937 - 2² = 21106991933 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21106991933) 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, 206931243 + ... + 206931344.

It is an arithmetic number, because the mean of its divisors is an integer number (3724763292).

Almost surely, 2^21106991937 is an apocalyptic number.

It is an amenable number.

21106991937 is a deficient number, since it is larger than the sum of its proper divisors (8691114399).

21106991937 is a wasteful number, since it uses less digits than its factorization.

21106991937 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 413862607.

The product of its (nonzero) digits is 183708, while the sum is 48.

The spelling of 21106991937 in words is "twenty-one billion, one hundred six million, nine hundred ninety-one thousand, nine hundred thirty-seven".