21501283464 has 224 divisors, whose sum is σ = 62656181280. Its totient is φ = 6909380352.

The previous prime is 21501283451. The next prime is 21501283621. The reversal of 21501283464 is 46438210512.

It is a happy number.

21501283464 is a `hidden beast` number, since 21 + 50 + 128 + 3 + 464 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 55 ways as a sum of consecutive naturals, for example, 20813892 + ... + 20814924.

It is an arithmetic number, because the mean of its divisors is an integer number (279715095).

Almost surely, 2^21501283464 is an apocalyptic number.

21501283464 is a gapful number since it is divisible by the number (24) 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 21501283464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31328090640).

21501283464 is an abundant number, since it is smaller than the sum of its proper divisors (41154897816).

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

21501283464 is a wasteful number, since it uses less digits than its factorization.

21501283464 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1183 (or 1164 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 36.

Adding to 21501283464 its reverse (46438210512), we get a palindrome (67939493976).

The spelling of 21501283464 in words is "twenty-one billion, five hundred one million, two hundred eighty-three thousand, four hundred sixty-four".