77421720 has 64 divisors (see below), whose sum is σ = 232852320. Its totient is φ = 20593664.

The previous prime is 77421691. The next prime is 77421761. The reversal of 77421720 is 2712477.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

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 15 ways as a sum of consecutive naturals, for example, 80764 + ... + 81716.

Almost surely, 2^77421720 is an apocalyptic number.

It is an amenable number.

77421720 is an abundant number, since it is smaller than the sum of its proper divisors (155430600).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

77421720 is a wasteful number, since it uses less digits than its factorization.

77421720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1644 (or 1640 counting only the distinct ones).

The product of its (nonzero) digits is 5488, while the sum is 30.

The square root of 77421720 is about 8798.9613023356. The cubic root of 77421720 is about 426.2073534845.

The spelling of 77421720 in words is "seventy-seven million, four hundred twenty-one thousand, seven hundred twenty".