21121525775 has 36 divisors (see below), whose sum is σ = 31000172112. Its totient is φ = 13983809280.

The previous prime is 21121525729. The next prime is 21121525783. The reversal of 21121525775 is 57752512112.

It is a happy number.

It is not a de Polignac number, because 21121525775 - 2³⁴ = 3941656591 is a prime.

It is a super-2 number, since 2×21121525775² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 75419 + ... + 218931.

It is an arithmetic number, because the mean of its divisors is an integer number (861115892).

Almost surely, 2^21121525775 is an apocalyptic number.

21121525775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21121525775 is a deficient number, since it is larger than the sum of its proper divisors (9878646337).

21121525775 is a wasteful number, since it uses less digits than its factorization.

21121525775 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 143588 (or 143554 counting only the distinct ones).

The product of its digits is 49000, while the sum is 38.

The spelling of 21121525775 in words is "twenty-one billion, one hundred twenty-one million, five hundred twenty-five thousand, seven hundred seventy-five".