64921440 has 96 divisors (see below), whose sum is σ = 211147776. Its totient is φ = 16750080.

The previous prime is 64921399. The next prime is 64921447. The reversal of 64921440 is 4412946.

It is a tau number, because it is divible by the number of its divisors (96).

It is a hoax number, since the sum of its digits (30) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 64921398 and 64921407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64921447) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12699 + ... + 17061.

It is an arithmetic number, because the mean of its divisors is an integer number (2199456).

Almost surely, 2^64921440 is an apocalyptic number.

64921440 is a gapful number since it is divisible by the number (60) 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 64921440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (105573888).

64921440 is an abundant number, since it is smaller than the sum of its proper divisors (146226336).

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

64921440 is a wasteful number, since it uses less digits than its factorization.

64921440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4412 (or 4404 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 30.

The square root of 64921440 is about 8057.3841909146. The cubic root of 64921440 is about 401.9105268561.

The spelling of 64921440 in words is "sixty-four million, nine hundred twenty-one thousand, four hundred forty".