21773812 has 6 divisors (see below), whose sum is σ = 38104178. Its totient is φ = 10886904.

The previous prime is 21773803. The next prime is 21773813. The reversal of 21773812 is 21837712.

It can be written as a sum of positive squares in only one way, i.e., 17757796 + 4016016 = 4214^2 + 2004^2 .

It is a super-2 number, since 2×21773812² = 948197778022688, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21773813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2721723 + ... + 2721730.

Almost surely, 2^21773812 is an apocalyptic number.

It is an amenable number.

21773812 is a deficient number, since it is larger than the sum of its proper divisors (16330366).

21773812 is a wasteful number, since it uses less digits than its factorization.

21773812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5443457 (or 5443455 counting only the distinct ones).

The product of its digits is 4704, while the sum is 31.

The square root of 21773812 is about 4666.2417425590. The cubic root of 21773812 is about 279.2403388048.

The spelling of 21773812 in words is "twenty-one million, seven hundred seventy-three thousand, eight hundred twelve".