21251442541 has 12 divisors (see below), whose sum is σ = 24743541312. Its totient is φ = 18198961368.

The previous prime is 21251442539. The next prime is 21251442559. The reversal of 21251442541 is 14524415212.

It is not a de Polignac number, because 21251442541 - 2¹ = 21251442539 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251442041) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 142555 + ... + 250648.

It is an arithmetic number, because the mean of its divisors is an integer number (2061961776).

Almost surely, 2^21251442541 is an apocalyptic number.

It is an amenable number.

21251442541 is a deficient number, since it is larger than the sum of its proper divisors (3492098771).

21251442541 is a wasteful number, since it uses less digits than its factorization.

21251442541 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 394320 (or 394313 counting only the distinct ones).

The product of its digits is 12800, while the sum is 31.

Adding to 21251442541 its reverse (14524415212), we get a palindrome (35775857753).

The spelling of 21251442541 in words is "twenty-one billion, two hundred fifty-one million, four hundred forty-two thousand, five hundred forty-one".