77740921 has 4 divisors (see below), whose sum is σ = 77766052. Its totient is φ = 77715792.

The previous prime is 77740919. The next prime is 77740933. The reversal of 77740921 is 12904777.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8185321 + 69555600 = 2861^2 + 8340^2 .

It is a cyclic number.

It is not a de Polignac number, because 77740921 - 2¹ = 77740919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (77740121) 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, 7146 + ... + 14371.

It is an arithmetic number, because the mean of its divisors is an integer number (19441513).

Almost surely, 2^77740921 is an apocalyptic number.

It is an amenable number.

77740921 is a deficient number, since it is larger than the sum of its proper divisors (25131).

77740921 is a wasteful number, since it uses less digits than its factorization.

77740921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25130.

The product of its (nonzero) digits is 24696, while the sum is 37.

The square root of 77740921 is about 8817.0812063857. The cubic root of 77740921 is about 426.7922852640.

The spelling of 77740921 in words is "seventy-seven million, seven hundred forty thousand, nine hundred twenty-one".