21777473 has 6 divisors (see below), whose sum is σ = 22020354. Its totient is φ = 21535584.

The previous prime is 21777467. The next prime is 21777487. The reversal of 21777473 is 37477712.

It is a happy number.

21777473 is nontrivially palindromic in base 16.

It can be written as a sum of positive squares in only one way, i.e., 12334144 + 9443329 = 3512^2 + 3073^2 .

It is not a de Polignac number, because 21777473 - 2¹⁰ = 21776449 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21777073) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 49388 + ... + 49826.

It is an arithmetic number, because the mean of its divisors is an integer number (3670059).

Almost surely, 2^21777473 is an apocalyptic number.

It is an amenable number.

21777473 is a deficient number, since it is larger than the sum of its proper divisors (242881).

21777473 is an frugal number, since it uses more digits than its factorization.

21777473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 991 (or 552 counting only the distinct ones).

The product of its digits is 57624, while the sum is 38.

The square root of 21777473 is about 4666.6340117905. The cubic root of 21777473 is about 279.2559882095.

The spelling of 21777473 in words is "twenty-one million, seven hundred seventy-seven thousand, four hundred seventy-three".