21077579 has 4 divisors (see below), whose sum is σ = 21099840. Its totient is φ = 21055320.

The previous prime is 21077561. The next prime is 21077599. The reversal of 21077579 is 97577012.

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

It is a cyclic number.

It is not a de Polignac number, because 21077579 - 2²⁴ = 4300363 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21077549) 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, 9644 + ... + 11625.

It is an arithmetic number, because the mean of its divisors is an integer number (5274960).

Almost surely, 2^21077579 is an apocalyptic number.

21077579 is a deficient number, since it is larger than the sum of its proper divisors (22261).

21077579 is an equidigital number, since it uses as much as digits as its factorization.

21077579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22260.

The product of its (nonzero) digits is 30870, while the sum is 38.

The square root of 21077579 is about 4591.0324546882. The cubic root of 21077579 is about 276.2317375641.

The spelling of 21077579 in words is "twenty-one million, seventy-seven thousand, five hundred seventy-nine".