21406751520 has 576 divisors, whose sum is σ = 86554935936. Its totient is φ = 4397137920.

The previous prime is 21406751519. The next prime is 21406751549. The reversal of 21406751520 is 2515760412.

It is a Harshad number since it is a multiple of its sum of digits (33).

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, 25095414 + ... + 25096266.

It is an arithmetic number, because the mean of its divisors is an integer number (150268986).

Almost surely, 2^21406751520 is an apocalyptic number.

21406751520 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 21406751520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (43277467968).

21406751520 is an abundant number, since it is smaller than the sum of its proper divisors (65148184416).

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

21406751520 is a wasteful number, since it uses less digits than its factorization.

21406751520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 993 (or 978 counting only the distinct ones).

The product of its (nonzero) digits is 16800, while the sum is 33.

The spelling of 21406751520 in words is "twenty-one billion, four hundred six million, seven hundred fifty-one thousand, five hundred twenty".