21051954 has 128 divisors (see below), whose sum is σ = 59996160. Its totient is φ = 5313600.

The previous prime is 21051949. The next prime is 21051977. The reversal of 21051954 is 45915012.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 253597 + ... + 253679.

It is an arithmetic number, because the mean of its divisors is an integer number (468720).

Almost surely, 2^21051954 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21051954, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29998080).

21051954 is an abundant number, since it is smaller than the sum of its proper divisors (38944206).

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

21051954 is a wasteful number, since it uses less digits than its factorization.

21051954 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 173 (or 167 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 27.

The square root of 21051954 is about 4588.2408393632. The cubic root of 21051954 is about 276.1197495484.

Adding to 21051954 its reverse (45915012), we get a palindrome (66966966).

The spelling of 21051954 in words is "twenty-one million, fifty-one thousand, nine hundred fifty-four".