21858144025 has 9 divisors (see below), whose sum is σ = 27105015261. Its totient is φ = 17485923840.

The previous prime is 21858144023. The next prime is 21858144031. The reversal of 21858144025 is 52044185812.

The square root of 21858144025 is 147845.

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

It can be written as a sum of positive squares in 4 ways, for example, as 247968009 + 21610176016 = 15747^2 + 147004^2 .

It is not a de Polignac number, because 21858144025 - 2¹ = 21858144023 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21858144023) 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, 724441 + ... + 754009.

Almost surely, 2^21858144025 is an apocalyptic number.

21858144025 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21858144025 is the 147845-th square number.

21858144025 is the 73923-rd centered octagonal number.

It is an amenable number.

21858144025 is a deficient number, since it is larger than the sum of its proper divisors (5246871236).

21858144025 is an frugal number, since it uses more digits than its factorization.

21858144025 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59148 (or 29574 counting only the distinct ones).

The product of its (nonzero) digits is 102400, while the sum is 40.

The spelling of 21858144025 in words is "twenty-one billion, eight hundred fifty-eight million, one hundred forty-four thousand, twenty-five".