21369977 has 4 divisors (see below), whose sum is σ = 21732240. Its totient is φ = 21007716.

The previous prime is 21369949. The next prime is 21369989. The reversal of 21369977 is 77996312.

It is a happy number.

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 21369977 - 2¹⁰ = 21368953 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21369917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181043 + ... + 181160.

It is an arithmetic number, because the mean of its divisors is an integer number (5433060).

Almost surely, 2^21369977 is an apocalyptic number.

It is an amenable number.

21369977 is a deficient number, since it is larger than the sum of its proper divisors (362263).

21369977 is an equidigital number, since it uses as much as digits as its factorization.

21369977 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 362262.

The product of its digits is 142884, while the sum is 44.

The square root of 21369977 is about 4622.7672448437. The cubic root of 21369977 is about 277.5032145287.

The spelling of 21369977 in words is "twenty-one million, three hundred sixty-nine thousand, nine hundred seventy-seven".