21020454 has 96 divisors (see below), whose sum is σ = 57605184. Its totient is φ = 5391360.

The previous prime is 21020437. The next prime is 21020501. The reversal of 21020454 is 45402012.

21020454 is a `hidden beast` number, since 210 + 2 + 0 + 454 = 666.

It is a super-2 number, since 2×21020454² = 883718972732232, which contains 22 as substring.

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

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 47 ways as a sum of consecutive naturals, for example, 67002 + ... + 67314.

It is an arithmetic number, because the mean of its divisors is an integer number (600054).

Almost surely, 2^21020454 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21020454, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28802592).

21020454 is an abundant number, since it is smaller than the sum of its proper divisors (36584730).

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

21020454 is a wasteful number, since it uses less digits than its factorization.

21020454 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 382 (or 379 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 18.

The square root of 21020454 is about 4584.8068661613. The cubic root of 21020454 is about 275.9819616440.

Adding to 21020454 its reverse (45402012), we get a palindrome (66422466).

The spelling of 21020454 in words is "twenty-one million, twenty thousand, four hundred fifty-four".