21112109947 has 2 divisors, whose sum is σ = 21112109948. Its totient is φ = 21112109946.

The previous prime is 21112109933. The next prime is 21112109983. The reversal of 21112109947 is 74990121112.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112109947 is a prime.

It is not a weakly prime, because it can be changed into another prime (21112109917) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10556054973 + 10556054974.

It is an arithmetic number, because the mean of its divisors is an integer number (10556054974).

Almost surely, 2^21112109947 is an apocalyptic number.

21112109947 is a deficient number, since it is larger than the sum of its proper divisors (1).

21112109947 is an equidigital number, since it uses as much as digits as its factorization.

21112109947 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 9072, while the sum is 37.

The spelling of 21112109947 in words is "twenty-one billion, one hundred twelve million, one hundred nine thousand, nine hundred forty-seven".