21012451040 has 48 divisors (see below), whose sum is σ = 56733620832. Its totient is φ = 7204268544.

The previous prime is 21012451007. The next prime is 21012451049. The reversal of 21012451040 is 4015421012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012451049) 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, 9379439 + ... + 9381678.

It is an arithmetic number, because the mean of its divisors is an integer number (1181950434).

Almost surely, 2^21012451040 is an apocalyptic number.

21012451040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21012451040 is an abundant number, since it is smaller than the sum of its proper divisors (35721169792).

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

21012451040 is a wasteful number, since it uses less digits than its factorization.

21012451040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18761139 (or 18761131 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

Adding to 21012451040 its reverse (4015421012), we get a palindrome (25027872052).

The spelling of 21012451040 in words is "twenty-one billion, twelve million, four hundred fifty-one thousand, forty".