64021815 has 48 divisors (see below), whose sum is σ = 130384800. Its totient is φ = 28650240.

The previous prime is 64021799. The next prime is 64021829. The reversal of 64021815 is 51812046.

64021815 is a `hidden beast` number, since 640 + 2 + 1 + 8 + 15 = 666.

It is not a de Polignac number, because 64021815 - 2⁴ = 64021799 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1461 + ... + 11409.

It is an arithmetic number, because the mean of its divisors is an integer number (2716350).

Almost surely, 2^64021815 is an apocalyptic number.

64021815 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

64021815 is an abundant number, since it is smaller than the sum of its proper divisors (66362985).

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

64021815 is a wasteful number, since it uses less digits than its factorization.

64021815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9984 (or 9981 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 64021815 is about 8001.3633213347. The cubic root of 64021815 is about 400.0454427539.

The spelling of 64021815 in words is "sixty-four million, twenty-one thousand, eight hundred fifteen".