21275775540 has 288 divisors, whose sum is σ = 71111040000. Its totient is φ = 5128427520.

The previous prime is 21275775533. The next prime is 21275775551. The reversal of 21275775540 is 4557757212.

21275775540 is a `hidden beast` number, since 2 + 1 + 27 + 5 + 77 + 554 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 7738086 + ... + 7740834.

Almost surely, 2^21275775540 is an apocalyptic number.

21275775540 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 21275775540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35555520000).

21275775540 is an abundant number, since it is smaller than the sum of its proper divisors (49835264460).

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

21275775540 is a wasteful number, since it uses less digits than its factorization.

21275775540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2887 (or 2882 counting only the distinct ones).

The product of its (nonzero) digits is 686000, while the sum is 45.

The spelling of 21275775540 in words is "twenty-one billion, two hundred seventy-five million, seven hundred seventy-five thousand, five hundred forty".