77542221 has 4 divisors (see below), whose sum is σ = 103389632. Its totient is φ = 51694812.

The previous prime is 77542207. The next prime is 77542271. The reversal of 77542221 is 12224577.

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 not a de Polignac number, because 77542221 - 2¹⁰ = 77541197 is a prime.

It is a super-2 number, since 2×77542221² = 12025592075225682, which contains 22 as substring.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (77542271) 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, 12923701 + ... + 12923706.

It is an arithmetic number, because the mean of its divisors is an integer number (25847408).

Almost surely, 2^77542221 is an apocalyptic number.

It is an amenable number.

77542221 is a deficient number, since it is larger than the sum of its proper divisors (25847411).

77542221 is a wasteful number, since it uses less digits than its factorization.

77542221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25847410.

The product of its digits is 7840, while the sum is 30.

The square root of 77542221 is about 8805.8060959801. The cubic root of 77542221 is about 426.4283586072.

Adding to 77542221 its reverse (12224577), we get a palindrome (89766798).

The spelling of 77542221 in words is "seventy-seven million, five hundred forty-two thousand, two hundred twenty-one".