21125040001 has 4 divisors (see below), whose sum is σ = 22750043092. Its totient is φ = 19500036912.

The previous prime is 21125039989. The next prime is 21125040011. The reversal of 21125040001 is 10004052112.

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 10100250000 + 11024790001 = 100500^2 + 104999^2 .

It is a cyclic number.

It is not a de Polignac number, because 21125040001 - 2⁹ = 21125039489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21125040011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 812501526 + ... + 812501551.

It is an arithmetic number, because the mean of its divisors is an integer number (5687510773).

Almost surely, 2^21125040001 is an apocalyptic number.

It is an amenable number.

21125040001 is a deficient number, since it is larger than the sum of its proper divisors (1625003091).

21125040001 is a wasteful number, since it uses less digits than its factorization.

21125040001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1625003090.

The product of its (nonzero) digits is 80, while the sum is 16.

Adding to 21125040001 its reverse (10004052112), we get a palindrome (31129092113).

The spelling of 21125040001 in words is "twenty-one billion, one hundred twenty-five million, forty thousand, one".