21115025401 has 4 divisors (see below), whose sum is σ = 21269149812. Its totient is φ = 20960900992.

The previous prime is 21115025383. The next prime is 21115025497. The reversal of 21115025401 is 10452051112.

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 4535887801 + 16579137600 = 67349^2 + 128760^2 .

It is a cyclic number.

It is not a de Polignac number, because 21115025401 - 2⁷ = 21115025273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21115025201) 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, 77062000 + ... + 77062273.

It is an arithmetic number, because the mean of its divisors is an integer number (5317287453).

Almost surely, 2^21115025401 is an apocalyptic number.

It is an amenable number.

21115025401 is a deficient number, since it is larger than the sum of its proper divisors (154124411).

21115025401 is a wasteful number, since it uses less digits than its factorization.

21115025401 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 154124410.

The product of its (nonzero) digits is 400, while the sum is 22.

Adding to 21115025401 its reverse (10452051112), we get a palindrome (31567076513).

The spelling of 21115025401 in words is "twenty-one billion, one hundred fifteen million, twenty-five thousand, four hundred one".