21051534145 has 4 divisors (see below), whose sum is σ = 25261840980. Its totient is φ = 16841227312.

The previous prime is 21051534143. The next prime is 21051534191. The reversal of 21051534145 is 54143515012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15926692401 + 5124841744 = 126201^2 + 71588^2 .

It is a cyclic number.

It is not a de Polignac number, because 21051534145 - 2¹ = 21051534143 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21051534143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2105153410 + ... + 2105153419.

It is an arithmetic number, because the mean of its divisors is an integer number (6315460245).

Almost surely, 2^21051534145 is an apocalyptic number.

It is an amenable number.

21051534145 is a deficient number, since it is larger than the sum of its proper divisors (4210306835).

21051534145 is an equidigital number, since it uses as much as digits as its factorization.

21051534145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4210306834.

The product of its (nonzero) digits is 12000, while the sum is 31.

The spelling of 21051534145 in words is "twenty-one billion, fifty-one million, five hundred thirty-four thousand, one hundred forty-five".