77820157791 has 12 divisors (see below), whose sum is σ = 112447062000. Its totient is φ = 51861566400.

The previous prime is 77820157787. The next prime is 77820157799. The reversal of 77820157791 is 19775102877.

It is not a de Polignac number, because 77820157791 - 2² = 77820157787 is a prime.

It is a super-2 number, since 2×77820157791² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77820157799) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1518291 + ... + 1568708.

It is an arithmetic number, because the mean of its divisors is an integer number (9370588500).

Almost surely, 2^77820157791 is an apocalyptic number.

77820157791 is a deficient number, since it is larger than the sum of its proper divisors (34626904209).

77820157791 is a wasteful number, since it uses less digits than its factorization.

77820157791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3089806 (or 3089803 counting only the distinct ones).

The product of its (nonzero) digits is 1728720, while the sum is 54.

The spelling of 77820157791 in words is "seventy-seven billion, eight hundred twenty million, one hundred fifty-seven thousand, seven hundred ninety-one".