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64991021 = 593109597
BaseRepresentation
bin1111011111101…
…0111100101101
311112021212220212
43313322330231
5113114203041
610240552205
71416262124
oct367727455
9145255825
1064991021
113375a797
1219922665
1310606934
1488baabb
155a8b8eb
hex3dfaf2d

64991021 has 4 divisors (see below), whose sum is σ = 65101212. Its totient is φ = 64880832.

The previous prime is 64990999. The next prime is 64991029. The reversal of 64991021 is 12019946.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 57229225 + 7761796 = 7565^2 + 2786^2 .

It is a cyclic number.

It is not a de Polignac number, because 64991021 - 26 = 64990957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (64991029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 54206 + ... + 55391.

It is an arithmetic number, because the mean of its divisors is an integer number (16275303).

Almost surely, 264991021 is an apocalyptic number.

It is an amenable number.

64991021 is a deficient number, since it is larger than the sum of its proper divisors (110191).

64991021 is a wasteful number, since it uses less digits than its factorization.

64991021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110190.

The product of its (nonzero) digits is 3888, while the sum is 32.

The square root of 64991021 is about 8061.7008751255. The cubic root of 64991021 is about 402.0540611107.

The spelling of 64991021 in words is "sixty-four million, nine hundred ninety-one thousand, twenty-one".

Divisors: 1 593 109597 64991021