21051790 has 32 divisors (see below), whose sum is σ = 39813120. Its totient is φ = 8004000.

The previous prime is 21051769. The next prime is 21051799. The reversal of 21051790 is 9715012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21051799) by changing a digit.

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, 17715 + ... + 18865.

It is an arithmetic number, because the mean of its divisors is an integer number (1244160).

Almost surely, 2^21051790 is an apocalyptic number.

21051790 is a deficient number, since it is larger than the sum of its proper divisors (18761330).

21051790 is a wasteful number, since it uses less digits than its factorization.

21051790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1248.

The product of its (nonzero) digits is 630, while the sum is 25.

The square root of 21051790 is about 4588.2229675551. Note that the first 3 decimals coincide. The cubic root of 21051790 is about 276.1190325325.

The spelling of 21051790 in words is "twenty-one million, fifty-one thousand, seven hundred ninety".