21257090 has 16 divisors (see below), whose sum is σ = 38835072. Its totient is φ = 8375664.

The previous prime is 21257077. The next prime is 21257101. The reversal of 21257090 is 9075212.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15194 + ... + 16533.

It is an arithmetic number, because the mean of its divisors is an integer number (2427192).

Almost surely, 2^21257090 is an apocalyptic number.

21257090 is a deficient number, since it is larger than the sum of its proper divisors (17577982).

21257090 is a wasteful number, since it uses less digits than its factorization.

21257090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31801.

The product of its (nonzero) digits is 1260, while the sum is 26.

The square root of 21257090 is about 4610.5411829849. The cubic root of 21257090 is about 277.0137142571.

The spelling of 21257090 in words is "twenty-one million, two hundred fifty-seven thousand, ninety".