21977773 has 4 divisors (see below), whose sum is σ = 22488928. Its totient is φ = 21466620.

The previous prime is 21977771. The next prime is 21977777. The reversal of 21977773 is 37777912.

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 21977773 - 2¹ = 21977771 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (43), and also a Moran number because the ratio is a prime number: 511111 = 21977773 / (2 + 1 + 9 + 7 + 7 + 7 + 7 + 3).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21977771) 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, 255513 + ... + 255598.

It is an arithmetic number, because the mean of its divisors is an integer number (5622232).

Almost surely, 2^21977773 is an apocalyptic number.

It is an amenable number.

21977773 is a deficient number, since it is larger than the sum of its proper divisors (511155).

21977773 is an equidigital number, since it uses as much as digits as its factorization.

21977773 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 511154.

The product of its digits is 129654, while the sum is 43.

The square root of 21977773 is about 4688.0457548962. The cubic root of 21977773 is about 280.1095362254.

The spelling of 21977773 in words is "twenty-one million, nine hundred seventy-seven thousand, seven hundred seventy-three".