21860090 has 64 divisors (see below), whose sum is σ = 47001600. Its totient is φ = 7166016.

The previous prime is 21860077. The next prime is 21860099. The reversal of 21860090 is 9006812.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21860099) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 276671 + ... + 276749.

It is an arithmetic number, because the mean of its divisors is an integer number (734400).

Almost surely, 2^21860090 is an apocalyptic number.

21860090 is an abundant number, since it is smaller than the sum of its proper divisors (25141510).

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

21860090 is a wasteful number, since it uses less digits than its factorization.

21860090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 21860090 is about 4675.4775157197. The cubic root of 21860090 is about 279.6086795463.

The spelling of 21860090 in words is "twenty-one million, eight hundred sixty thousand, ninety".