21901023 has 20 divisors (see below), whose sum is σ = 32989440. Its totient is φ = 14478912.

The previous prime is 21901021. The next prime is 21901051. The reversal of 21901023 is 32010912.

It is a happy number.

It is not a de Polignac number, because 21901023 - 2¹ = 21901021 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21900987 and 21901005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21901021) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 9223 + ... + 11351.

It is an arithmetic number, because the mean of its divisors is an integer number (1649472).

Almost surely, 2^21901023 is an apocalyptic number.

21901023 is a deficient number, since it is larger than the sum of its proper divisors (11088417).

21901023 is a wasteful number, since it uses less digits than its factorization.

21901023 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2268 (or 2259 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21901023 is about 4679.8528823030. The cubic root of 21901023 is about 279.7830930670.

Adding to 21901023 its reverse (32010912), we get a palindrome (53911935).

The spelling of 21901023 in words is "twenty-one million, nine hundred one thousand, twenty-three".