21040001251 has 8 divisors (see below), whose sum is σ = 21153775104. Its totient is φ = 20926493640.

The previous prime is 21040001243. The next prime is 21040001267. The reversal of 21040001251 is 15210004012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21040001251 - 2³ = 21040001243 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21040001221) 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 7 ways as a sum of consecutive naturals, for example, 92946 + ... + 225208.

It is an arithmetic number, because the mean of its divisors is an integer number (2644221888).

Almost surely, 2^21040001251 is an apocalyptic number.

21040001251 is a deficient number, since it is larger than the sum of its proper divisors (113773853).

21040001251 is a wasteful number, since it uses less digits than its factorization.

21040001251 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133121.

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

Adding to 21040001251 its reverse (15210004012), we get a palindrome (36250005263).

The spelling of 21040001251 in words is "twenty-one billion, forty million, one thousand, two hundred fifty-one".