21245123534 has 4 divisors (see below), whose sum is σ = 31867685304. Its totient is φ = 10622561766.

The previous prime is 21245123531. The next prime is 21245123551. The reversal of 21245123534 is 43532154212.

It is a semiprime because it is the product of two primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21245123534.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21245123531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5311280882 + ... + 5311280885.

It is an arithmetic number, because the mean of its divisors is an integer number (7966921326).

Almost surely, 2^21245123534 is an apocalyptic number.

21245123534 is a deficient number, since it is larger than the sum of its proper divisors (10622561770).

21245123534 is a wasteful number, since it uses less digits than its factorization.

21245123534 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10622561769.

The product of its digits is 28800, while the sum is 32.

Adding to 21245123534 its reverse (43532154212), we get a palindrome (64777277746).

The spelling of 21245123534 in words is "twenty-one billion, two hundred forty-five million, one hundred twenty-three thousand, five hundred thirty-four".