64021440 has 168 divisors, whose sum is σ = 236628432. Its totient is φ = 14622720.

The previous prime is 64021423. The next prime is 64021457. The reversal of 64021440 is 4412046.

It is an interprime number because it is at equal distance from previous prime (64021423) and next prime (64021457).

It is a tau number, because it is divible by the number of its divisors (168).

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 46360 + ... + 47720.

Almost surely, 2^64021440 is an apocalyptic number.

64021440 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 64021440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (118314216).

64021440 is an abundant number, since it is smaller than the sum of its proper divisors (172606992).

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

64021440 is a wasteful number, since it uses less digits than its factorization.

64021440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1395 (or 1378 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 21.

The square root of 64021440 is about 8001.3398877938. The cubic root of 64021440 is about 400.0446616798.

Adding to 64021440 its reverse (4412046), we get a palindrome (68433486).

The spelling of 64021440 in words is "sixty-four million, twenty-one thousand, four hundred forty".