77721281 has 8 divisors (see below), whose sum is σ = 86855328. Its totient is φ = 68932000.

The previous prime is 77721277. The next prime is 77721313. The reversal of 77721281 is 18212777.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 77721281 - 2² = 77721277 is a prime.

It is a super-2 number, since 2×77721281² = 12081195040561922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77721211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 85715 + ... + 86616.

It is an arithmetic number, because the mean of its divisors is an integer number (10856916).

Almost surely, 2^77721281 is an apocalyptic number.

It is an amenable number.

77721281 is a deficient number, since it is larger than the sum of its proper divisors (9134047).

77721281 is a wasteful number, since it uses less digits than its factorization.

77721281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172383.

The product of its digits is 10976, while the sum is 35.

The square root of 77721281 is about 8815.9673887782. The cubic root of 77721281 is about 426.7563414892.

The spelling of 77721281 in words is "seventy-seven million, seven hundred twenty-one thousand, two hundred eighty-one".