21401252505 has 24 divisors (see below), whose sum is σ = 37703632200. Its totient is φ = 11226885120.

The previous prime is 21401252449. The next prime is 21401252531. The reversal of 21401252505 is 50525210412.

21401252505 is a `hidden beast` number, since 2 + 1 + 401 + 2 + 5 + 250 + 5 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 45522009 + 21355730496 = 6747^2 + 146136^2 .

It is not a de Polignac number, because 21401252505 - 2⁶ = 21401252441 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3895480 + ... + 3900969.

It is an arithmetic number, because the mean of its divisors is an integer number (1570984675).

Almost surely, 2^21401252505 is an apocalyptic number.

It is an amenable number.

21401252505 is a deficient number, since it is larger than the sum of its proper divisors (16302379695).

21401252505 is a wasteful number, since it uses less digits than its factorization.

21401252505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7796521 (or 7796518 counting only the distinct ones).

The product of its (nonzero) digits is 4000, while the sum is 27.

Adding to 21401252505 its reverse (50525210412), we get a palindrome (71926462917).

The spelling of 21401252505 in words is "twenty-one billion, four hundred one million, two hundred fifty-two thousand, five hundred five".