77121556 has 24 divisors (see below), whose sum is σ = 141714720. Its totient is φ = 36671712.

The previous prime is 77121491. The next prime is 77121557. The reversal of 77121556 is 65512177.

It is a happy number.

It is a super-2 number, since 2×77121556² = 11895468799722272, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77121557) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2811 + ... + 12733.

It is an arithmetic number, because the mean of its divisors is an integer number (5904780).

Almost surely, 2^77121556 is an apocalyptic number.

It is an amenable number.

77121556 is a deficient number, since it is larger than the sum of its proper divisors (64593164).

77121556 is a wasteful number, since it uses less digits than its factorization.

77121556 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10023 (or 10021 counting only the distinct ones).

The product of its digits is 14700, while the sum is 34.

The square root of 77121556 is about 8781.8879519156. The cubic root of 77121556 is about 425.6558381733.

It can be divided in two parts, 77121 and 556, that added together give a palindrome (77677).

The spelling of 77121556 in words is "seventy-seven million, one hundred twenty-one thousand, five hundred fifty-six".