21881572 has 6 divisors (see below), whose sum is σ = 38292758. Its totient is φ = 10940784.

The previous prime is 21881557. The next prime is 21881581. The reversal of 21881572 is 27518812.

It can be written as a sum of positive squares in only one way, i.e., 20304036 + 1577536 = 4506^2 + 1256^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 2735193 + ... + 2735200.

Almost surely, 2^21881572 is an apocalyptic number.

It is an amenable number.

21881572 is a deficient number, since it is larger than the sum of its proper divisors (16411186).

21881572 is a wasteful number, since it uses less digits than its factorization.

21881572 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5470397 (or 5470395 counting only the distinct ones).

The product of its digits is 8960, while the sum is 34.

The square root of 21881572 is about 4677.7742570586. The cubic root of 21881572 is about 279.7002404254.

The spelling of 21881572 in words is "twenty-one million, eight hundred eighty-one thousand, five hundred seventy-two".