21031790 has 16 divisors (see below), whose sum is σ = 40769568. Its totient is φ = 7765536.

The previous prime is 21031781. The next prime is 21031793. The reversal of 21031790 is 9713012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21031793) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 80762 + ... + 81021.

It is an arithmetic number, because the mean of its divisors is an integer number (2548098).

Almost surely, 2^21031790 is an apocalyptic number.

21031790 is a deficient number, since it is larger than the sum of its proper divisors (19737778).

21031790 is a wasteful number, since it uses less digits than its factorization.

21031790 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161803.

The product of its (nonzero) digits is 378, while the sum is 23.

The square root of 21031790 is about 4586.0429566239. The cubic root of 21031790 is about 276.0315636380.

The spelling of 21031790 in words is "twenty-one million, thirty-one thousand, seven hundred ninety".