21851838414025 has 9 divisors (see below), whose sum is σ = 27096308615911. Its totient is φ = 17481452032840.

The previous prime is 21851838414023. The next prime is 21851838414041. The reversal of 21851838414025 is 52041483815812.

The square root of 21851838414025 is 4674595.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 7866661829049 + 13985176584976 = 2804757^2 + 3739676^2 .

It is not a de Polignac number, because 21851838414025 - 2¹ = 21851838414023 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21851838414023) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 22905516 + ... + 23840434.

Almost surely, 2^{21851838414025} is an apocalyptic number.

21851838414025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21851838414025 is the 4674595-th square number.

21851838414025 is the 2337298-th centered octagonal number.

It is an amenable number.

21851838414025 is a deficient number, since it is larger than the sum of its proper divisors (5244470201886).

21851838414025 is an frugal number, since it uses more digits than its factorization.

21851838414025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1869848 (or 934924 counting only the distinct ones).

The product of its (nonzero) digits is 2457600, while the sum is 52.

The spelling of 21851838414025 in words is "twenty-one trillion, eight hundred fifty-one billion, eight hundred thirty-eight million, four hundred fourteen thousand, twenty-five".