21790121 has 8 divisors (see below), whose sum is σ = 22381920. Its totient is φ = 21202272.

The previous prime is 21790099. The next prime is 21790123. The reversal of 21790121 is 12109712.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21790121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21790123) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12650 + ... + 14268.

It is an arithmetic number, because the mean of its divisors is an integer number (2797740).

Almost surely, 2^21790121 is an apocalyptic number.

It is an amenable number.

21790121 is a deficient number, since it is larger than the sum of its proper divisors (591799).

21790121 is a wasteful number, since it uses less digits than its factorization.

21790121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1975.

The product of its (nonzero) digits is 252, while the sum is 23.

The square root of 21790121 is about 4667.9889674248. The cubic root of 21790121 is about 279.3100401830.

Adding to 21790121 its reverse (12109712), we get a palindrome (33899833).

The spelling of 21790121 in words is "twenty-one million, seven hundred ninety thousand, one hundred twenty-one".