21771812 has 12 divisors (see below), whose sum is σ = 38623116. Its totient is φ = 10736640.

The previous prime is 21771811. The next prime is 21771833. The reversal of 21771812 is 21817712.

It can be written as a sum of positive squares in 2 ways, for example, as 12432676 + 9339136 = 3526^2 + 3056^2 .

It is not an unprimeable number, because it can be changed into a prime (21771811) 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, 36989 + ... + 37572.

It is an arithmetic number, because the mean of its divisors is an integer number (3218593).

Almost surely, 2^21771812 is an apocalyptic number.

It is an amenable number.

21771812 is a deficient number, since it is larger than the sum of its proper divisors (16851304).

21771812 is a wasteful number, since it uses less digits than its factorization.

21771812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74638 (or 74636 counting only the distinct ones).

The product of its digits is 1568, while the sum is 29.

The square root of 21771812 is about 4666.0274324097. The cubic root of 21771812 is about 279.2317888124.

The spelling of 21771812 in words is "twenty-one million, seven hundred seventy-one thousand, eight hundred twelve".