77821738 has 4 divisors (see below), whose sum is σ = 116732610. Its totient is φ = 38910868.

The previous prime is 77821727. The next prime is 77821759. The reversal of 77821738 is 83712877.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 83712877 = 631 ⋅132667.

It can be written as a sum of positive squares in only one way, i.e., 42810849 + 35010889 = 6543^2 + 5917^2 .

It is a junction number, because it is equal to n+sod(n) for n = 77821694 and 77821703.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19455433 + ... + 19455436.

Almost surely, 2^77821738 is an apocalyptic number.

77821738 is a deficient number, since it is larger than the sum of its proper divisors (38910872).

77821738 is a wasteful number, since it uses less digits than its factorization.

77821738 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38910871.

The product of its digits is 131712, while the sum is 43.

The square root of 77821738 is about 8821.6629951501. The cubic root of 77821738 is about 426.9401272940.

The spelling of 77821738 in words is "seventy-seven million, eight hundred twenty-one thousand, seven hundred thirty-eight".