2121640236409 has 2 divisors, whose sum is σ = 2121640236410. Its totient is φ = 2121640236408.

The previous prime is 2121640236389. The next prime is 2121640236431. The reversal of 2121640236409 is 9046320461212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1988108460009 + 133531776400 = 1410003^2 + 365420^2 .

It is a cyclic number.

It is not a de Polignac number, because 2121640236409 - 2²⁵ = 2121606681977 is a prime.

It is not a weakly prime, because it can be changed into another prime (2121640206409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1060820118204 + 1060820118205.

It is an arithmetic number, because the mean of its divisors is an integer number (1060820118205).

Almost surely, 2^{2121640236409} is an apocalyptic number.

It is an amenable number.

2121640236409 is a deficient number, since it is larger than the sum of its proper divisors (1).

2121640236409 is an equidigital number, since it uses as much as digits as its factorization.

2121640236409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 124416, while the sum is 40.

The spelling of 2121640236409 in words is "two trillion, one hundred twenty-one billion, six hundred forty million, two hundred thirty-six thousand, four hundred nine".