2101221231961 has 2 divisors, whose sum is σ = 2101221231962. Its totient is φ = 2101221231960.

The previous prime is 2101221231871. The next prime is 2101221232001. The reversal of 2101221231961 is 1691321221012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1238679961600 + 862541270361 = 1112960^2 + 928731^2 .

It is a cyclic number.

It is not a de Polignac number, because 2101221231961 - 2¹⁵ = 2101221199193 is a prime.

It is not a weakly prime, because it can be changed into another prime (2101221231061) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1050610615980 + 1050610615981.

It is an arithmetic number, because the mean of its divisors is an integer number (1050610615981).

Almost surely, 2^{2101221231961} is an apocalyptic number.

It is an amenable number.

2101221231961 is a deficient number, since it is larger than the sum of its proper divisors (1).

2101221231961 is an equidigital number, since it uses as much as digits as its factorization.

2101221231961 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 31.

Adding to 2101221231961 its reverse (1691321221012), we get a palindrome (3792542452973).

The spelling of 2101221231961 in words is "two trillion, one hundred one billion, two hundred twenty-one million, two hundred thirty-one thousand, nine hundred sixty-one".