7877790981 has 6 divisors (see below), whose sum is σ = 11379031430. Its totient is φ = 5251860648.

The previous prime is 7877790971. The next prime is 7877791037. The reversal of 7877790981 is 1890977787.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 5082977025 + 2794813956 = 71295^2 + 52866^2 .

It is not a de Polignac number, because 7877790981 - 2⁶ = 7877790917 is a prime.

It is a super-2 number, since 2×7877790981² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7877790941) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 437655046 + ... + 437655063.

Almost surely, 2^7877790981 is an apocalyptic number.

It is an amenable number.

7877790981 is a deficient number, since it is larger than the sum of its proper divisors (3501240449).

7877790981 is a wasteful number, since it uses less digits than its factorization.

7877790981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 875310115 (or 875310112 counting only the distinct ones).

The product of its (nonzero) digits is 12446784, while the sum is 63.

The square root of 7877790981 is about 88756.9207498773. The cubic root of 7877790981 is about 1989.7636126542.

The spelling of 7877790981 in words is "seven billion, eight hundred seventy-seven million, seven hundred ninety thousand, nine hundred eighty-one".