21221012101997 has 2 divisors, whose sum is σ = 21221012101998. Its totient is φ = 21221012101996.

The previous prime is 21221012101967. The next prime is 21221012102033. The reversal of 21221012101997 is 79910121012212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13755597993316 + 7465414108681 = 3708854^2 + 2732291^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21221012101997 is a prime.

It is a super-3 number, since 3×21221012101997³ (a number of 41 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21221012101997.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21221012101967) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10610506050998 + 10610506050999.

It is an arithmetic number, because the mean of its divisors is an integer number (10610506050999).

Almost surely, 2^{21221012101997} is an apocalyptic number.

It is an amenable number.

21221012101997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21221012101997 is an equidigital number, since it uses as much as digits as its factorization.

21221012101997 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 38.

The spelling of 21221012101997 in words is "twenty-one trillion, two hundred twenty-one billion, twelve million, one hundred one thousand, nine hundred ninety-seven".