21221001090 has 96 divisors (see below), whose sum is σ = 56732809536. Its totient is φ = 5499480960.

The previous prime is 21221001059. The next prime is 21221001097. The reversal of 21221001090 is 9010012212.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (21221001097) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 3230149 + ... + 3236711.

It is an arithmetic number, because the mean of its divisors is an integer number (590966766).

Almost surely, 2^21221001090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21221001090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28366404768).

21221001090 is an abundant number, since it is smaller than the sum of its proper divisors (35511808446).

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

21221001090 is a wasteful number, since it uses less digits than its factorization.

21221001090 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7584 (or 7581 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The spelling of 21221001090 in words is "twenty-one billion, two hundred twenty-one million, one thousand, ninety".