20919890 has 16 divisors (see below), whose sum is σ = 37719000. Its totient is φ = 8353920.

The previous prime is 20919883. The next prime is 20919919. The reversal of 20919890 is 9891902.

It can be written as a sum of positive squares in 4 ways, for example, as 5230369 + 15689521 = 2287^2 + 3961^2 .

It is a super-2 number, since 2×20919890² = 875283595224200, which contains 22 as substring.

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, 6236 + ... + 8984.

Almost surely, 2^20919890 is an apocalyptic number.

20919890 is a deficient number, since it is larger than the sum of its proper divisors (16799110).

20919890 is a wasteful number, since it uses less digits than its factorization.

20919890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3517.

The product of its (nonzero) digits is 11664, while the sum is 38.

The square root of 20919890 is about 4573.8266254855. The cubic root of 20919890 is about 275.5411492955.

The spelling of 20919890 in words is "twenty million, nine hundred nineteen thousand, eight hundred ninety".