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21191678818 = 2191518910691
BaseRepresentation
bin10011101111000111…
…110101101101100010
32000200212212211021021
4103233013311231202
5321400032210233
613422455120054
71350102204112
oct235707655542
960625784237
1021191678818
118a95171a52
12413507302a
131cc954772b
14105068b042
158406b0e2d
hex4ef1f5b62

21191678818 has 16 divisors (see below), whose sum is σ = 31963092480. Its totient is φ = 10537346800.

The previous prime is 21191678813. The next prime is 21191678887. The reversal of 21191678818 is 81887619112.

It is a super-2 number, since 2×211916788182 (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21191678813) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1976853 + ... + 1987543.

It is an arithmetic number, because the mean of its divisors is an integer number (1997693280).

Almost surely, 221191678818 is an apocalyptic number.

21191678818 is a deficient number, since it is larger than the sum of its proper divisors (10771413662).

21191678818 is a wasteful number, since it uses less digits than its factorization.

21191678818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16073.

The product of its digits is 387072, while the sum is 52.

The spelling of 21191678818 in words is "twenty-one billion, one hundred ninety-one million, six hundred seventy-eight thousand, eight hundred eighteen".

Divisors: 1 2 191 382 5189 10378 10691 21382 991099 1982198 2041981 4083962 55475599 110951198 10595839409 21191678818