21254123520 has 1248 divisors, whose sum is σ = 96562060800. Its totient is φ = 4331667456.

The previous prime is 21254123489. The next prime is 21254123551. The reversal of 21254123520 is 2532145212.

21254123520 is a `hidden beast` number, since 2 + 12 + 5 + 4 + 123 + 520 = 666.

It is an interprime number because it is at equal distance from previous prime (21254123489) and next prime (21254123551).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1118638071 + ... + 1118638089.

Almost surely, 2^21254123520 is an apocalyptic number.

21254123520 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21254123520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (48281030400).

21254123520 is an abundant number, since it is smaller than the sum of its proper divisors (75307937280).

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

21254123520 is a wasteful number, since it uses less digits than its factorization.

21254123520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 98 (or 53 counting only the distinct ones).

The product of its (nonzero) digits is 4800, while the sum is 27.

Adding to 21254123520 its reverse (2532145212), we get a palindrome (23786268732).

The spelling of 21254123520 in words is "twenty-one billion, two hundred fifty-four million, one hundred twenty-three thousand, five hundred twenty".