21001129997 has 2 divisors, whose sum is σ = 21001129998. Its totient is φ = 21001129996.

The previous prime is 21001129993. The next prime is 21001130009. The reversal of 21001129997 is 79992110012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16908841156 + 4092288841 = 130034^2 + 63971^2 .

It is a cyclic number.

It is not a de Polignac number, because 21001129997 - 2² = 21001129993 is a prime.

It is a super-2 number, since 2×21001129997² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21001129993) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10500564998 + 10500564999.

It is an arithmetic number, because the mean of its divisors is an integer number (10500564999).

Almost surely, 2^21001129997 is an apocalyptic number.

It is an amenable number.

21001129997 is a deficient number, since it is larger than the sum of its proper divisors (1).

21001129997 is an equidigital number, since it uses as much as digits as its factorization.

21001129997 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 20412, while the sum is 41.

The spelling of 21001129997 in words is "twenty-one billion, one million, one hundred twenty-nine thousand, nine hundred ninety-seven".