77721047 has 2 divisors, whose sum is σ = 77721048. Its totient is φ = 77721046.

The previous prime is 77721037. The next prime is 77721067. The reversal of 77721047 is 74012777.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 77721047 - 2⁸ = 77720791 is a prime.

It is a super-2 number, since 2×77721047² = 12081122293552418, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 77720998 and 77721016.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (77721037) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 38860523 + 38860524.

It is an arithmetic number, because the mean of its divisors is an integer number (38860524).

Almost surely, 2^77721047 is an apocalyptic number.

77721047 is a deficient number, since it is larger than the sum of its proper divisors (1).

77721047 is an equidigital number, since it uses as much as digits as its factorization.

77721047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19208, while the sum is 35.

The square root of 77721047 is about 8815.9541173942. The cubic root of 77721047 is about 426.7559132021.

The spelling of 77721047 in words is "seventy-seven million, seven hundred twenty-one thousand, forty-seven".