21251442534 has 16 divisors (see below), whose sum is σ = 48574725888. Its totient is φ = 6071840712.

The previous prime is 21251442481. The next prime is 21251442539. The reversal of 21251442534 is 43524415212.

It is a junction number, because it is equal to n+sod(n) for n = 21251442495 and 21251442504.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21251442539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 252993322 + ... + 252993405.

It is an arithmetic number, because the mean of its divisors is an integer number (3035920368).

Almost surely, 2^21251442534 is an apocalyptic number.

21251442534 is an abundant number, since it is smaller than the sum of its proper divisors (27323283354).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21251442534 is a wasteful number, since it uses less digits than its factorization.

21251442534 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 505986739.

The product of its digits is 38400, while the sum is 33.

Adding to 21251442534 its reverse (43524415212), we get a palindrome (64775857746).

The spelling of 21251442534 in words is "twenty-one billion, two hundred fifty-one million, four hundred forty-two thousand, five hundred thirty-four".