21120021111997 has 2 divisors, whose sum is σ = 21120021111998. Its totient is φ = 21120021111996.

The previous prime is 21120021111991. The next prime is 21120021112009. The reversal of 21120021111997 is 79911112002112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 11777669923321 + 9342351188676 = 3431861^2 + 3056526^2 .

It is a cyclic number.

It is not a de Polignac number, because 21120021111997 - 2²³ = 21120012723389 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21120021111991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560010555998 + 10560010555999.

It is an arithmetic number, because the mean of its divisors is an integer number (10560010555999).

Almost surely, 2^{21120021111997} is an apocalyptic number.

It is an amenable number.

21120021111997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21120021111997 is an equidigital number, since it uses as much as digits as its factorization.

21120021111997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4536, while the sum is 37.

The spelling of 21120021111997 in words is "twenty-one trillion, one hundred twenty billion, twenty-one million, one hundred eleven thousand, nine hundred ninety-seven".