21771490 has 32 divisors (see below), whose sum is σ = 42448896. Its totient is φ = 7992000.

The previous prime is 21771487. The next prime is 21771521. The reversal of 21771490 is 9417712.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28615 + ... + 29365.

It is an arithmetic number, because the mean of its divisors is an integer number (1326528).

Almost surely, 2^21771490 is an apocalyptic number.

21771490 is a deficient number, since it is larger than the sum of its proper divisors (20677406).

21771490 is a wasteful number, since it uses less digits than its factorization.

21771490 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 994.

The product of its (nonzero) digits is 3528, while the sum is 31.

The square root of 21771490 is about 4665.9929275557. The cubic root of 21771490 is about 279.2304122147.

The spelling of 21771490 in words is "twenty-one million, seven hundred seventy-one thousand, four hundred ninety".