21799890 has 48 divisors (see below), whose sum is σ = 64778688. Its totient is φ = 4982688.

The previous prime is 21799889. The next prime is 21799901. The reversal of 21799890 is 9899712.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16672 + ... + 17931.

It is an arithmetic number, because the mean of its divisors is an integer number (1349556).

Almost surely, 2^21799890 is an apocalyptic number.

21799890 is an abundant number, since it is smaller than the sum of its proper divisors (42978798).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21799890 is a wasteful number, since it uses less digits than its factorization.

21799890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34623 (or 34620 counting only the distinct ones).

The product of its (nonzero) digits is 81648, while the sum is 45.

The square root of 21799890 is about 4669.0352322509. The cubic root of 21799890 is about 279.3517742655.

The spelling of 21799890 in words is "twenty-one million, seven hundred ninety-nine thousand, eight hundred ninety".