77564021 has 4 divisors (see below), whose sum is σ = 78656544. Its totient is φ = 76471500.

The previous prime is 77563973. The next prime is 77564029. The reversal of 77564021 is 12046577.

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 77564021 - 2¹⁸ = 77301877 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 (77564029) 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, 546155 + ... + 546296.

It is an arithmetic number, because the mean of its divisors is an integer number (19664136).

Almost surely, 2^77564021 is an apocalyptic number.

77564021 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

It is an amenable number.

77564021 is a deficient number, since it is larger than the sum of its proper divisors (1092523).

77564021 is a wasteful number, since it uses less digits than its factorization.

77564021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1092522.

The product of its (nonzero) digits is 11760, while the sum is 32.

The square root of 77564021 is about 8807.0438286635. The cubic root of 77564021 is about 426.4683164825.

The spelling of 77564021 in words is "seventy-seven million, five hundred sixty-four thousand, twenty-one".