21004254040 has 256 divisors, whose sum is σ = 60406456320. Its totient is φ = 6383370240.

The previous prime is 21004254031. The next prime is 21004254049. The reversal of 21004254040 is 4045240012.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21004254031) and next prime (21004254049).

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21004254049) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 36402232 + ... + 36402808.

It is an arithmetic number, because the mean of its divisors is an integer number (235962720).

Almost surely, 2^21004254040 is an apocalyptic number.

21004254040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21004254040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30203228160).

21004254040 is an abundant number, since it is smaller than the sum of its proper divisors (39402202280).

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

21004254040 is a wasteful number, since it uses less digits than its factorization.

21004254040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 882 (or 878 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

Adding to 21004254040 its reverse (4045240012), we get a palindrome (25049494052).

The spelling of 21004254040 in words is "twenty-one billion, four million, two hundred fifty-four thousand, forty".