21645142025 has 24 divisors (see below), whose sum is σ = 28942902744. Its totient is φ = 15962918400.

The previous prime is 21645142009. The next prime is 21645142049. The reversal of 21645142025 is 52024154612.

It can be written as a sum of positive squares in 12 ways, for example, as 20720738809 + 924403216 = 143947^2 + 30404^2 .

It is not a de Polignac number, because 21645142025 - 2⁴ = 21645142009 is a prime.

It is a super-2 number, since 2×21645142025² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21645141982 and 21645142000.

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, 203567 + ... + 291083.

It is an arithmetic number, because the mean of its divisors is an integer number (1205954281).

Almost surely, 2^21645142025 is an apocalyptic number.

21645142025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21645142025 is a deficient number, since it is larger than the sum of its proper divisors (7297760719).

21645142025 is a wasteful number, since it uses less digits than its factorization.

21645142025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88301 (or 88296 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 32.

Adding to 21645142025 its reverse (52024154612), we get a palindrome (73669296637).

The spelling of 21645142025 in words is "twenty-one billion, six hundred forty-five million, one hundred forty-two thousand, twenty-five".