21551421040 has 40 divisors (see below), whose sum is σ = 50176877760. Its totient is φ = 8608555776.

The previous prime is 21551421019. The next prime is 21551421053. The reversal of 21551421040 is 4012415512.

It is a tau number, because it is divible by the number of its divisors (40).

It is a junction number, because it is equal to n+sod(n) for n = 21551420996 and 21551421014.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 129819 + ... + 244858.

It is an arithmetic number, because the mean of its divisors is an integer number (1254421944).

Almost surely, 2^21551421040 is an apocalyptic number.

21551421040 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21551421040 is an abundant number, since it is smaller than the sum of its proper divisors (28625456720).

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

21551421040 is a wasteful number, since it uses less digits than its factorization.

21551421040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 375409 (or 375403 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 25.

Adding to 21551421040 its reverse (4012415512), we get a palindrome (25563836552).

The spelling of 21551421040 in words is "twenty-one billion, five hundred fifty-one million, four hundred twenty-one thousand, forty".