21121111001971 has 2 divisors, whose sum is σ = 21121111001972. Its totient is φ = 21121111001970.

The previous prime is 21121111001941. The next prime is 21121111002053. The reversal of 21121111001971 is 17910011112112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21121111001971 - 2³⁷ = 20983672048499 is a prime.

It is a super-2 number, since 2×21121111001971² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21121111001941) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10560555500985 + 10560555500986.

It is an arithmetic number, because the mean of its divisors is an integer number (10560555500986).

Almost surely, 2^{21121111001971} is an apocalyptic number.

21121111001971 is a deficient number, since it is larger than the sum of its proper divisors (1).

21121111001971 is an equidigital number, since it uses as much as digits as its factorization.

21121111001971 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 252, while the sum is 28.

The spelling of 21121111001971 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred eleven million, one thousand, nine hundred seventy-one".