81907777749 has 48 divisors (see below), whose sum is σ = 138040903680. Its totient is φ = 42910650720.

The previous prime is 81907777739. The next prime is 81907777759. The reversal of 81907777749 is 94777770918.

It is an interprime number because it is at equal distance from previous prime (81907777739) and next prime (81907777759).

It is not a de Polignac number, because 81907777749 - 2⁴ = 81907777733 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81907777749.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81907777739) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 386419 + ... + 559584.

It is an arithmetic number, because the mean of its divisors is an integer number (2875852160).

Almost surely, 2^81907777749 is an apocalyptic number.

It is an amenable number.

81907777749 is a deficient number, since it is larger than the sum of its proper divisors (56133125931).

81907777749 is a wasteful number, since it uses less digits than its factorization.

81907777749 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 946070 (or 946063 counting only the distinct ones).

The product of its (nonzero) digits is 43563744, while the sum is 66.

The spelling of 81907777749 in words is "eighty-one billion, nine hundred seven million, seven hundred seventy-seven thousand, seven hundred forty-nine".