6840121978591 has 4 divisors (see below), whose sum is σ = 7461951249384. Its totient is φ = 6218292707800.

The previous prime is 6840121978589. The next prime is 6840121978603. The reversal of 6840121978591 is 1958791210486.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6840121978591 - 2¹ = 6840121978589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6840121978531) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 310914635380 + ... + 310914635401.

It is an arithmetic number, because the mean of its divisors is an integer number (1865487812346).

Almost surely, 2^{6840121978591} is an apocalyptic number.

6840121978591 is a deficient number, since it is larger than the sum of its proper divisors (621829270793).

6840121978591 is a wasteful number, since it uses less digits than its factorization.

6840121978591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 621829270792.

The product of its (nonzero) digits is 8709120, while the sum is 61.

The spelling of 6840121978591 in words is "six trillion, eight hundred forty billion, one hundred twenty-one million, nine hundred seventy-eight thousand, five hundred ninety-one".