77400021 has 4 divisors (see below), whose sum is σ = 103200032. Its totient is φ = 51600012.

The previous prime is 77400019. The next prime is 77400077. The reversal of 77400021 is 12000477.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12000477 = 3 ⋅4000159.

It is not a de Polignac number, because 77400021 - 2¹ = 77400019 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77401021) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12900001 + ... + 12900006.

It is an arithmetic number, because the mean of its divisors is an integer number (25800008).

Almost surely, 2^77400021 is an apocalyptic number.

It is an amenable number.

77400021 is a deficient number, since it is larger than the sum of its proper divisors (25800011).

77400021 is a wasteful number, since it uses less digits than its factorization.

77400021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25800010.

The product of its (nonzero) digits is 392, while the sum is 21.

The square root of 77400021 is about 8797.7281726591. The cubic root of 77400021 is about 426.1675320257.

Adding to 77400021 its reverse (12000477), we get a palindrome (89400498).

The spelling of 77400021 in words is "seventy-seven million, four hundred thousand, twenty-one".