77988021 has 4 divisors (see below), whose sum is σ = 103984032. Its totient is φ = 51992012.

The previous prime is 77987981. The next prime is 77988049. The reversal of 77988021 is 12088977.

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.

It is a cyclic number.

It is not a de Polignac number, because 77988021 - 2⁶ = 77987957 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77988091) 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, 12998001 + ... + 12998006.

It is an arithmetic number, because the mean of its divisors is an integer number (25996008).

Almost surely, 2^77988021 is an apocalyptic number.

It is an amenable number.

77988021 is a deficient number, since it is larger than the sum of its proper divisors (25996011).

77988021 is a wasteful number, since it uses less digits than its factorization.

77988021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25996010.

The product of its (nonzero) digits is 56448, while the sum is 42.

The square root of 77988021 is about 8831.0826629581. The cubic root of 77988021 is about 427.2439943242.

The spelling of 77988021 in words is "seventy-seven million, nine hundred eighty-eight thousand, twenty-one".