21531424435240 has 32 divisors (see below), whose sum is σ = 50116246533000. Its totient is φ = 8315584609024.

The previous prime is 21531424435151. The next prime is 21531424435273. The reversal of 21531424435240 is 4253442413512.

It can be written as a sum of positive squares in 4 ways, for example, as 16762293495684 + 4769130939556 = 4094178^2 + 2183834^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 21531424435193 and 21531424435202.

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, 9280785235 + ... + 9280787554.

Almost surely, 2^{21531424435240} is an apocalyptic number.

21531424435240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21531424435240 is an abundant number, since it is smaller than the sum of its proper divisors (28584822097760).

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

21531424435240 is a wasteful number, since it uses less digits than its factorization.

21531424435240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18561572829 (or 18561572825 counting only the distinct ones).

The product of its (nonzero) digits is 460800, while the sum is 40.

Adding to 21531424435240 its reverse (4253442413512), we get a palindrome (25784866848752).

The spelling of 21531424435240 in words is "twenty-one trillion, five hundred thirty-one billion, four hundred twenty-four million, four hundred thirty-five thousand, two hundred forty".