21773651 has 4 divisors (see below), whose sum is σ = 23054472. Its totient is φ = 20492832.

The previous prime is 21773623. The next prime is 21773657. The reversal of 21773651 is 15637712.

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 21773651 - 2¹⁸ = 21511507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21773657) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 640385 + ... + 640418.

It is an arithmetic number, because the mean of its divisors is an integer number (5763618).

Almost surely, 2^21773651 is an apocalyptic number.

21773651 is a deficient number, since it is larger than the sum of its proper divisors (1280821).

21773651 is a wasteful number, since it uses less digits than its factorization.

21773651 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1280820.

The product of its digits is 8820, while the sum is 32.

The square root of 21773651 is about 4666.2244909563. The cubic root of 21773651 is about 279.2396505497.

The spelling of 21773651 in words is "twenty-one million, seven hundred seventy-three thousand, six hundred fifty-one".