21320890 has 32 divisors (see below), whose sum is σ = 40932864. Its totient is φ = 7968000.

The previous prime is 21320881. The next prime is 21320911. The reversal of 21320890 is 9802312.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28015 + ... + 28765.

It is an arithmetic number, because the mean of its divisors is an integer number (1279152).

Almost surely, 2^21320890 is an apocalyptic number.

21320890 is a deficient number, since it is larger than the sum of its proper divisors (19611974).

21320890 is a wasteful number, since it uses less digits than its factorization.

21320890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 942.

The product of its (nonzero) digits is 864, while the sum is 25.

The square root of 21320890 is about 4617.4549266885. The cubic root of 21320890 is about 277.2905759686.

The spelling of 21320890 in words is "twenty-one million, three hundred twenty thousand, eight hundred ninety".